Combination test method by using argon as gross-leak test tracer gas and using helium as fine-leak test tracer gas

ABSTRACT

The present invention discloses an improved method of combination test by using argon as gross-leak tracer gas and using helium as fine-leak tracer gas, belongs to the field of hermeticity test. The method is designed to solve the problem that the existing methods are not ideal when the component has lower τHemin and wider range of volume V. The invention comprises step S1 of selecting: using helium-argon prefilling method for the first hermeticity test and helium-argon pressuring method after helium-argon prefilling for repetitive hermeticity test, or using helium-argon pressuring method after argon prefilling for the first hermeticity test and helium-argon multi-pressuring method after argon prefilling for repetitive hermeticity tests. The improved method extends the maximum detection-waiting time, effectively prevents detection missing and misjudges in gross-leak/fine-leak test, and solves the detection problems on applicability, feasibility and credibility.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Chinese Patent Application No.201510199700.2, filed on Apr. 23, 2015, which is hereby incorporated byreference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the field of a hermeticity testmethod, particularly to a combination test method by using argon asgross-leak test tracer gas and using helium as fine-leak test tracergas.

BACKGROUND

The cumulative helium mass spectrometric combination leak test method,which uses helium as both gross-leak test tracer gas and fine-leak testtracer gas, is a hermeticity test method, but it is defective for itshigh detection missing rate and is questioned in credibility. Thus, animproved combination test method is proposed by using the argon asgross-leak test tracer gas.

This improved cumulative helium mass spectrometric combination testmethod, which is related the US Patent Application Publication No.US2015/0073726 A1, included using argon as gross-leak test tracer gasand using helium as fine-leak test tracer gas, in addition to a numberof other improvements. The Patent Application effectively extended therange of applicable rigor grade τ_(Hemin) and a cavity volume V for thecomponents under detection, and improved the credibility of detection.

The improved combination test method is still not ideal in thedetectable range of the cavity volume V when the components underdetection have lower rigor grade τ_(Hemin). And there is still a certaindetection missing rate of fine/gross-leak test, the credibility needsfurther improved.

SUMMARY

An embodiment of the present disclosure provides a combination testmethod by using argon as gross-leak test tracer gas and using helium asfine-leak test tracer gas, which is to further improve the existingimproved helium mass spectrometric combination test method, furtherextend the applicable range of rigor grade τ_(Hemin) and cavity volumeV, and improve the feasibility and credibility.

For this purpose, the present invention employs the following technicalsolutions.

The combination test method comprising the following steps: Step S1 ofselecting. The helium-argon prefilling method is selected for the firsthermeticity test, and the helium-argon pressuring method afterhelium-argon prefilling is selected for repetitive hermeticity test; thehelium-argon pressuring method after argon prefilling is selected forthe first hermeticity test, and helium-argon multi-pressuring methodafter argon prefilling is selected for repetitive hermeticity test; themeasured argon leak rate R_(Ar0max) is the criterion for gross-leaktest, and the rigor grade τ_(Hemin) is the basic criterion for fine-leaktest and the helium measured leak rate R_(max) is the characteristiccriterion; both the fixed scheme and the flexible scheme are selectedfor the first test, and the flexible scheme is selected for repetitivetests; for the fixed scheme, the rigor grade τ_(Hemin) is selected asthe value of 2000 days, 200 days, or 20 days, and the argon measuredleak rate criterion R_(Ar0max) is selected as the value of 7.95×10⁻⁴Pa·cm³/s, 2.39×10⁻³ Pa·cm³/s, 7.95×10⁻³ Pa·cm³/s or 2.39×10⁻² Pa·cm³/s;the rigor grade and criterion for the flexible scheme are selected thesame value as those for the fixed scheme, or other values.

In particular, in step S2, the parameters are designed according to thespecific method, scheme, τ_(Hemin) and R_(Ar0max) selected in step S1.the pressure and time conditions of helium-argon prefilling, argonprefilling, or helium-argon pressuring are designed in step S2.1; thehelium measured leak rate criterion of fine-leak test R_(max) isdesigned in step S2.2 and the maximum detection-waiting time t_(max) isdesigned in step S2.4; the maximum gross-leak detection time t_(4max),the maximum fine-leak detection time t_(5max), and the minimumdetection-waiting time t_(3min) of helium-argon prefilling method aredesigned in step S2.5; and the fixed scheme or the flexible scheme isdesigned in step S2.6.

In step S2.1, the pressure and time conditions of helium-argonprefilling, argon prefilling or helium-argon pressuring are designed:

if the first detection chooses helium-argon prefilling method, the totalgas pressure P is (1+10%)P₀ during seal, with helium part pressureP_(He) of (1+10%)kP₀, argon partial pressure P_(Ar) of (1+10%) P_(Ar0),and nitrogen of the rest, where P₀ is standard atmospheric pressure1.013×10⁵ Pa; k is the helium prefilling ratio P_(Hed)/P₀, whereinP_(Hed) is a helium partial pressure of a designed helium-argonprefilling when the total pre-inflation pressure is standard atmosphericpressure; and P_(Ar0) is the normal partial pressure of argon inatmosphere, P_(Ar0)=946 Pa;

for the fixed scheme, k=0.21 is chosen; and k is variable from 0.03 to0.5 for flexible scheme;

if helium-argon pressuring method after argon prefilling is selected forthe first detection, the total gas pressure P will be (1+10%)P₀ duringseal, with argon partial pressure (1+10%) P_(Ar0) and the rest ofnitrogen; the total pressure of bombed gas is no more than 6P₀, in whichthere is argon with the partial pressure P_(Ar) equal to P_(Ar0), andhelium with the partial pressure P_(E) no less than 2P₀. Thehelium-argon pressuring time t₁ is long enough to make sure that thehelium measured leak rate criterion R_(1max) reaches the detectablerange of detectors;

for the repetitive tests, if the helium-argon pressuring method afterhelium-argon prefilling is selected, in the nth (integers n is no lessthan 1) helium-argon pressuring, the argon partial pressure P_(Ar) isP_(Ar0), the helium partial pressure P_(En) is no less than 2P₀ toprevent the fine-leak detection missing; the helium-argon pressuringtime tin can be obtained by formula (1),

$\begin{matrix}\left. \begin{matrix}{t_{1n} \geqslant {\frac{1}{P_{En}}\left( {{\frac{1}{10e}{kP}_{0}t_{3.0n}} + {0.15{\sum\limits_{i = 1}^{n - 1}\;{P_{Ei}t_{1i}}}}} \right)}} \\{{t_{1n} \geqslant {1.2h}}\mspace{329mu}}\end{matrix} \right\} & (1)\end{matrix}$

where, t_(3.0n) is the interval time from the ending of sealing to theending of the nth helium-argon pressuring; P_(Ei) and t_(1i) are thehelium partial pressure and time in the ith helium-argon pressuring; and

for the repetitive tests, if the helium-argon multi-pressuring methodafter argon prefilling is selected, in the nth (n is no less than 2)helium-argon pressuring, the argon partial pressure P_(Ar) is P_(Ar0),and the helium partial pressure P_(En) is no less than 2P₀ to preventthe fine-leak detection missing; the helium-argon pressuring time tincan be obtained by formula (1) when k=0.

In step S2.2, the helium measured leak rate criterion R_(max) forfine-leak test is designed:

for the helium-argon prefilling method in first test, the componentsunder detection are stored for the detection-waiting time t₃ in thenormal atmosphere, the helium measured leak rate criterion R_(2max) ofthe fine-leak test can be obtained by formula (2),

$\begin{matrix}{R_{2\mspace{14mu}\max} = {\frac{{VkP}_{0}}{\tau_{{He}\mspace{14mu}\min}}{\exp\left( {- \frac{t_{3}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} & (2)\end{matrix}$

where, V denotes a cavity volume of the component under detection;

R_(2max) can be obtained by approximate formula (3) in the condition of

${t_{3} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$

$\begin{matrix}{R_{2\mspace{14mu}\max} = \frac{{VkP}_{0}}{\tau_{{He}\mspace{14mu}\min}}} & (3)\end{matrix}$

for the helium-argon pressuring method after argon prefilling in thefirst test, the components under detection are stored in air after seal,bombed helium-argon for time t₁ and then stored for detection-waitingtime t₂, the helium measured leak rate criterion R_(2max) of thefine-leak test can be obtained by formula (4),

$\begin{matrix}{R_{1\;\max} = {{\frac{{VP}_{E}}{\tau_{{He}\mspace{14mu}\min}}\left\lbrack {1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} & (4)\end{matrix}$

or R_(1max) is obtained by approximate formula (5) in the condition of

$t_{1} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{2}} \leqslant {\frac{1}{10}{\tau_{{He}\mspace{14mu}\min}.}}$

$\begin{matrix}{R_{1\max} = \frac{{VP}_{E}t_{1}}{\tau_{{He}\mspace{14mu}\min}^{2}}} & (5)\end{matrix}$

for the helium-argon pressuring method after helium-argon prefilling inthe repetitive tests, the helium measured leak rate criterion R_(2n.max)of fine-leak test after the nth (n is no less than 1) helium-argonpressuring can be obtained by formula (6),

$\begin{matrix}{R_{2{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} + {\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}}} \right\}{\exp\left( {- \frac{t_{2n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} & (6)\end{matrix}$

where, t_(2.in) is the interval time from the ending of the ithhelium-argon pressuring to the ending of nth helium-argon pressuring;and t_(2n) is the detection-waiting time in normal air after the nthhelium-argon pressuring.

Similarly, R_(2n.max) can be obtained by approximate formula (7) in thecondition of

${t_{1i} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu}\min}}},{t_{2n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$

$\begin{matrix}{R_{2{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} + {\frac{1}{\tau_{{He}\mspace{14mu}\min}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}}}} \right\}}} & (7)\end{matrix}$

for the repetitive tests, in the condition of

${t_{3.0n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{2n}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$R_(2n.max) can also be obtained by approximate formula (8),

$\begin{matrix}{R_{2{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left( {{kP}_{0} + {\frac{1}{\tau_{{He}\mspace{14mu}\min}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}}}}} \right)}} & (8)\end{matrix}$

furthermore, when

$\left( {\frac{1}{\tau_{{He}\mspace{14mu}\min}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}}}} \right) \leqslant {\frac{1}{10}{kP}_{0}}$in the formula (8), R_(2n.max) can be obtained by formula (9),

$\begin{matrix}{R_{2{n.\max}} = \frac{{VkP}_{0}}{\tau_{{He}\mspace{14mu}\min}}} & (9)\end{matrix}$

for the helium-argon multi-pressuring method after argon prefilling inthe repetitive tests, the helium measured leak rate criterion R_(1n.max)of fine-leak test after the nth (n is no less than 2) helium-argonpressuring can be obtained by formula (10),

$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left\{ {\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} \right\}{\exp\left( {- \frac{t_{2n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} & (10)\end{matrix}$

or, R_(1n.max) can be obtained by approximate formula (11) in thecondition of

${t_{1i} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu}\min}}},{t_{2n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$

$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}^{2}}\left\lbrack {\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} \right\rbrack}} & (11)\end{matrix}$

furthermore, when

$t_{2.{in}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{1i}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}$in formula (11), R_(1n.max) can be obtained by formula (12),

$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{20mu}\min}^{2}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}}}}} & (12)\end{matrix}$

in step S2.3, the upper limit of the cavity volume can be obtained byformula (13),

$\begin{matrix}{V_{\max} = {\frac{L_{\max\; 0}\tau_{{He}\mspace{14mu}\min}}{P_{0}}\sqrt{\frac{M_{A}}{M_{He}}}}} & (13)\end{matrix}$

where, L_(max0) is the maximum detectable equivalent standard leak rate,L_(max)=1.0 Pa·cm³/s; M_(He) is the molecular weight of helium in grams,M_(He)=4.003 g; and M_(A) is the average molecular weight of air ingrams, M_(A)=28.96 g.

In step S2.4, the maximum detection-waiting time t_(max) of fine-leaktest is designed:

corresponding to the argon measured leak rate criterion R_(Ar0max) ofgross-leak rate test R_(0max), which is the helium measured leak ratecriterion of gross-leak rate test when the helium partial pressureP_(He) is equal to P_(He0) in the component under test, can be obtainedby formula (14),

$\begin{matrix}{R_{0\mspace{14mu}\max} = {R_{{Ar}\; 0\mspace{14mu}\max}\frac{P_{{He}\; 0}}{P_{{Ar}\; 0}}\sqrt{\frac{M_{Ar}}{M_{He}}}}} & (14)\end{matrix}$

where, P_(He0) is the helium partial pressure in normal atmosphere,P_(He0)=0.533 Pa; M_(Ar) is the molecular weight of argon in grams,M_(Ar)=39.948 g;

the helium exchange time constant τ_(He0) of gross-leak can be obtainedby formula (15),

$\begin{matrix}{\tau_{{He}\; 0} = {{\frac{{VP}_{0}}{L_{0}}\sqrt{\frac{M_{He}}{M_{A}}}} = {\frac{{VP}_{{He}\; 0}}{R_{0\mspace{14mu}\max}} = {\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\; 0\max}}\sqrt{\frac{M_{He}}{M_{Ar}}}}}}} & (15)\end{matrix}$

where, L₀ is the minimum detectable equivalent standard leak rate forgross-leak test,

${L_{0} = {R_{{Ar}\; 0\mspace{14mu}\max}\frac{P_{0}}{P_{{Ar}\; 0}}\sqrt{\frac{M_{Ar}}{M_{A}}}}};$

the argon exchange time constant τ_(Ar0) of gross-leak can be obtainedby formula (16),

$\begin{matrix}{\tau_{{Ar}\; 0} = {\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\; 0\max}} = {\tau_{{He}\; 0}\sqrt{\frac{M_{Ar}}{M_{He}}}}}} & (16)\end{matrix}$

the helium exchange time constant τ_(He0.m) of medium-leak can beobtained by formula (17),

$\begin{matrix}{\tau_{{He}\; 0.m} = {\tau_{{He}\; 0}\frac{R_{0\max}}{R_{\max}}}} & (17)\end{matrix}$

where, the fine-leak helium measured leak rate criterion R_(max) is lessthan R_(0max);

for helium-argon prefilling method, when τ_(Hemin)>τ_(He0) andR_(2max)≥R_(0max), the maximum detection-waiting time of fine-leak testor combination test t_(3max) can be obtained by formula (18),

$\begin{matrix}{t_{3\max} = {{\frac{\tau_{Hemin}\tau_{{He}\; 0}}{\tau_{Hemin} - \tau_{{He}\; 0}}{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0}} \right)}} = {\frac{\tau_{Hemin}{VP}_{{He}\; 0}}{{\tau_{Hemin}R_{0\max}} - {VP}_{{He}\; 0}}{\ln\left( \frac{\tau_{Hemin}R_{0\max}}{{VP}_{{He}\; 0}} \right)}}}} & (18)\end{matrix}$

for the fixed scheme, t_(3max) can be obtained by formula (19),

$\begin{matrix}\left. \begin{matrix}{t_{3\max} = {\frac{\tau_{Hemin}{VP}_{{He}\; 0}}{{\tau_{Hemin}R_{0\max}} - {VP}_{{He}\; 0}}{\ln\left( \frac{\tau_{Hemin}R_{0\max}}{{VP}_{{He}\; 0}} \right)}}} \\{t_{3\max} \leqslant {\frac{1}{10}\tau_{Hemin}}}\end{matrix} \right\} & (19)\end{matrix}$

for the helium-argon prefilling method, when τ_(Hemin)>τ_(He0) andR_(2max)<R_(0max), t_(3max) can be obtained by formula (20),

$\begin{matrix}{t_{3\max} = {\frac{\tau_{Hemin}\tau_{{He}\; 0.m}}{\tau_{Hemin} - \tau_{{He}\; 0.m}}{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0.m}} \right)}}} & (20)\end{matrix}$

for the fixed scheme, t_(3max) can be obtained by formula (21),

$\begin{matrix}\left. \begin{matrix}{t_{3\max} = {\frac{\tau_{Hemin}P_{{He}\; 0}}{{kP}_{0} - P_{{He}\; 0}}{\ln\left( \frac{{kP}_{0}}{P_{{He}\; 0}} \right)}}} \\{t_{3\max} \leqslant {\frac{1}{10}\tau_{Hemin}}}\end{matrix} \right\} & (21)\end{matrix}$

for the helium-argon pressuring method after argon prefilling, whenτ_(Hemin)>τ_(He0) and R_(1max)≥R_(0max), the maximum detection-waitingtime of fine-leak test t_(2max) can be obtained by formula (22),

$\begin{matrix}{t_{2\max} = {{\frac{\tau_{Hemin}\tau_{{He}\; 0}}{\tau_{Hemin} - \tau_{{He}\; 0}}\left\{ {{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\; 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{Hemin}}} \right)}} \right\rbrack}} \right\}} = {\frac{\tau_{Hemin}{VP}_{{He}\; 0}}{{\tau_{Hemin}R_{0\max}} - {VP}_{{He}\; 0}}\left\{ {{\ln\left( \frac{\tau_{Hemin}R_{0\max}}{{VP}_{{He}\; 0}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}R_{0\max}}{{VP}_{{He}\; 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{Hemin}}} \right)}} \right\rbrack}} \right\}}}} & (22)\end{matrix}$

for the fixed scheme, t_(2max) can be obtained by formula (23),

$\begin{matrix}\left. \begin{matrix}\begin{matrix}{t_{2\max} = {\frac{\tau_{Hemin}{VP}_{{He}\; 0}}{{\tau_{Hemin}R_{0\max}} - {VP}_{{He}\; 0}}\left\{ {{\ln\left( \frac{\tau_{Hemin}R_{0\max}}{{VP}_{{He}\; 0}} \right)} +} \right.}} \\\left. {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}R_{0\max}}{{VP}_{{He}\; 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{Hemin}}} \right)}} \right\rbrack} \right\}\end{matrix} \\{t_{2\max} \leqslant {\frac{1}{10}\tau_{Hemin}}}\end{matrix} \right\} & (23)\end{matrix}$

for the helium-argon pressuring method after argon prefilling, whenτ_(Hemin)>τ_(He0), R_(1max)<R_(0max), t_(2max) can be obtained byformula (24),

$\begin{matrix}{t_{2\max} = {\frac{\tau_{Hemin}\tau_{{He}\; 0.m}}{\tau_{Hemin} - \tau_{{He}\; 0.m}}\left\{ {{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0.m}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\; 0.m}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{Hemin}}} \right)}} \right\rbrack}} \right\}}} & (24)\end{matrix}$

for the fixed scheme, t_(2max) can be obtained by formula (25),

$\begin{matrix}\left. \begin{matrix}\begin{matrix}{t_{2\max} = {\frac{\tau_{Hemin}^{2}P_{{He}\; 0}}{{P_{E}t_{1}} - {P_{{He}\; 0}\tau_{Hemin}}}\left\{ {{\ln\left( \frac{P_{E}t_{1}}{P_{{He}\; 0}\tau_{Hemin}} \right)} +} \right.}} \\\left. {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{P_{E}t_{1}^{2}}{P_{{He}\; 0}\tau_{Hemin}^{2}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{Hemin}}} \right)}} \right\rbrack} \right\}\end{matrix} \\{t_{2\max} \leqslant {\frac{1}{10}\tau_{Hemin}}}\end{matrix} \right\} & (25)\end{matrix}$

for the helium-argon pressuring method after argon prefilling, after thenth (n is no less than 1) helium-argon pressuring, the maximumdetection-waiting time can be obtained by formula (26), whenτ_(Hemin)>τ_(He0) and R_(2n.max)≥R_(0max),

$\begin{matrix}{t_{3{n.\max}} = {\frac{\tau_{Hemin}\tau_{{He}\; 0}}{\tau_{Hemin} - \tau_{{He}\; 0}}{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0}} \right)}}} & (26)\end{matrix}$

in the condition of τ_(Hemin)>τ_(He0) and R_(2n.max)<R_(0max),t_(3n.max) can be obtained by formula (27),

$\begin{matrix}{t_{3{n.\max}} = {\frac{\tau_{Hemin}\tau_{{He}\; 0.m}}{\tau_{Hemin} - \tau_{{He}\; 0.m}}{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0.m}} \right)}}} & (27)\end{matrix}$

for the helium-argon pressuring method after argon prefilling, after thenth (n is no less than 2) helium-argon pressuring, the maximumdetection-waiting time of fine-leak t_(2n.max) can be obtained byformula (28), when τ_(Hemin)>τ_(He0) and R_(1n.max)≥R_(0max),

$\begin{matrix}{t_{2{n.\max}} = {\frac{\tau_{Hemin}\tau_{{He}\; 0}}{\tau_{Hemin} - \tau_{{He}\; 0}}{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0}} \right)}}} & (28)\end{matrix}$

in the condition of τ_(Hemin)>τ_(He0) and R_(1n.max)<R_(0max),t_(2n.max) can be obtained by formula (29),

$\begin{matrix}{t_{2{n.\max}} = {\frac{\tau_{Hemin}\tau_{{He}\; 0.m}}{\tau_{Hemin} - \tau_{{He}\; 0.m}}{\ln\left( \frac{\tau_{Hemin}}{\tau_{{He}\; 0.m}} \right)}}} & (29)\end{matrix}$

all the t_(max) (including t_(3max), t_(2max), t_(3n.max), t_(2n.max))are no less than 0.5 hours.

In step S2.5, in order to reduce or prevent detection missing ingross-leak test and fine-leak test, the parameters, including themaximum gross-leak detection time t_(4max), fine-leak detection timet_(5max) and the minimum detection-waiting time of helium-argonprefilling method t_(3min), are designed:

t_(4max) can be obtained by formula (30) when using one of the fourtypical hermeticity test methods (including helium-argon prefillingmethod, helium-argon pressuring method after argon prefilling,helium-argon pressuring method after helium-argon prefilling,helium-argon multi-pressuring method after argon prefilling),

$\begin{matrix}\left. \begin{matrix}{t_{4\max} = {{\frac{1}{10}\tau_{{Ar}\; 0}} = {\frac{1}{10}\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\; 0\max}}}}} \\{{30\mspace{14mu} s} \leqslant t_{4\max} \leqslant {900{\mspace{11mu}\;}s}}\end{matrix} \right\} & (30)\end{matrix}$

for the four typical hermeticity test methods, when the measured leakrate criterion of fine-leak test R_(max) (including R_(2max), R_(1max),R_(2n.max), R_(1n.max)) is no less than 0.905R_(0max), t_(5max) can beobtained by formula (31),

$\begin{matrix}\left. \begin{matrix}{t_{5\max} = {{\frac{1}{10}\tau_{{He}\; 0}} = {\frac{1}{10}\frac{{VP}_{0}}{L_{0}}\sqrt{\frac{M_{He}}{M_{A}}}}}} \\{{60\mspace{14mu} s} \leqslant t_{5\max} \leqslant {1200{\mspace{11mu}\;}s}}\end{matrix} \right\} & (31)\end{matrix}$

and for helium-argon prefilling method, t_(3min) can be obtained byformula (31),

$\begin{matrix}\left. \begin{matrix}{t_{3\mspace{14mu}\min} = {\tau_{{He}\; 0}\frac{1}{1 + {10l_{{He}.n}}}}} \\{{t_{3\mspace{14mu}\min} \leqslant {\frac{1}{3}t_{3\mspace{14mu}\max}}}} \\{{or}\mspace{230mu}} \\{{t_{3\mspace{14mu}\min} \leqslant {t_{3\mspace{14mu}\max} - {24h}}}\mspace{40mu}}\end{matrix} \right\} & (32)\end{matrix}$

where, l_(He.n) is the viscous conductance constant corresponding to L₀(Pa·cm³/s), when the pressures of both leak hole ends respectively areP₀ and 0, and can be obtained by formula (33),l _(He.n)=0.5L ₀ ^(0.314)  (33)

for the four typical hermeticity test methods, when R_(max) is less than0.905R_(0max), t_(5max) can be obtained by formula (34),

$\begin{matrix}\left. \begin{matrix}{t_{5\mspace{14mu}\max} = {\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\mspace{14mu} 0\mspace{14mu}\max}}\sqrt{\frac{M_{He}}{M_{Ar}}}{\ln\left( \frac{R_{0\mspace{14mu}\max}}{R_{\max}} \right)}}} \\{{{60s} \leqslant t_{5\max} \leqslant {1200s}}\mspace{175mu}}\end{matrix} \right\} & (34)\end{matrix}$

In step S2.6, the fixed scheme or flexible scheme is designed:

according to a certain cavity volume V, the selected τ_(Hemin) andR_(Ar0max), the flexible scheme can be designed for the combination testwith argon as gross-leak tracer gas and helium as fine-leak tracer gas.

for the components under detection with acceptable hermeticity rigorgrade τ_(Hemin), the maximum equivalent standard leak rate L_(max) canbe obtained by formula (35),

$\begin{matrix}{L_{\max} = {\frac{{VP}_{0}}{\tau_{{He}\mspace{14mu}\min}}\sqrt{\frac{M_{He}}{M_{A}}}}} & (35)\end{matrix}$

the range of cavity volume V, i.e. 0.0006 cm³˜200 cm³, is divided intodifferent segments, and then the fixed scheme of the helium-argonprefilling method and helium-argon pressuring method after argonprefilling is designed. In the design, R_(2max) can be obtained byformula (3) and R_(1max) by formula (5); the lower limit of a cavityvolume segment will be used when designing R_(2max), R_(1max), t_(3max),t_(2max), t_(4max), t_(5max) and L_(max); similarly, the upper limit ofV will be used when designing t_(3min).

In particular, in step S3, helium-argon or argon is prefilled duringsealing and helium-argon is pressured:

for the helium-argon prefilling method and helium-argon pressuringmethod after argon prefilling, the total pressure of prefilling gas P is(1+10%)P₀ with the argon partial pressure of (1+10%)946 Pa and thehelium part pressure as follows: for helium-argon prefilling method, thehelium pressure ratio k will be 21% in fixed scheme, or designed by stepS2 in flexible scheme. There is no helium in the prefilling gas forhelium-argon pressuring method after argon prefilling; and

for the fixed scheme and flexible scheme of helium-argon pressuringmethod after helium-argon prefilling, the flexible scheme ofhelium-argon pressuring method after argon prefilling and helium-argonmulti-pressuring method after argon prefilling, the argon pressure inhelium-argon pressuring gas is (1+10%)946 Pa, and helium pressuresP_(E), P_(En) is no less than 2P₀.

In particular, in step S4, removing the absorbed helium-argon andkeeping internal P_(Ar0) and P_(He0) are designed as follows:

in order to prevent detection missing or misjudge in gross-leak test,the component after sealing or helium-argon pressuring should be kept innormal dry air environment with normal argon and helium pressure; and

to prevent the detection missing in fine-leak/gross-leak test, thecomponents is stored in normal air for 3.23Δt at least to make the argonpartial pressure get back to no less than 0.9 P_(Ar0) and the heliumpartial pressure no less than 0.9P_(He0) if they experienced vacuumbaking or testing in the environment without normal helium and argon forΔt (Δt is no longer than ⅙t_(max)); the argon leak rate criterion changeinto 0.9R_(Ar0max) for gross-leak test. and the helium leak ratecriterion is still R_(max) for fine-leak test.

In particular, in step S6, the maximum and minimum detection-waitingtime of fine-leak test are compared:

for helium-argon prefilling method, the fine-leak test detection-waitingtime t₃ (between the ending of seal and the beginning of fine-leaktest), is no longer than t_(3max) designed in step S2.4; when thefine-leak measured leak rate R_(2max)≥0.905R_(0max), t₃ should be noless than t_(3min) designed in step S2.5; and

for the helium-argon pressuring method after argon prefilling, thehelium pressuring method after helium-argon prefilling and helium-argonmulti-pressuring method after argon prefilling, the maximumdetection-waiting time from the ending of the last helium-argonpressuring to the beginning of the combination test t₂, t_(3n) andt_(2n) is no more than t_(2max), t_(3max), t_(2n.max) designed in stepS2.4; if t₃>t_(3max), t₂>t_(2max), t_(3n)>t_(3n.max) ort_(2n)>t_(2n.max), the components are pressured helium-argon and beremoved absorbed helium-argon again before test.

In particular, in step S7, the gross-leak test is designed:

in order to prevent misjudge and reduce the detection missing ratio, thegross-leak detection time t₄, which is from putting in the test chamberto beginning to read the argon measured leak rate R_(Ar) of gross-leak,is no less than the minimum gross-leak detection time t_(4min) and nolonger than t_(4max) designed in step S2.5; t_(4min) is the longest timefor the background argon leak rate reducing to ⅓R_(Ar0max) in thecondition of stable test system and empty chamber; and

if the argon measured leak rate R_(Ar) is no less than R_(Ar0max), thecomponent is refused; else the component is accepted and the fine-leaktest can be done next.

In particular, in step S8, the fine-leak test is designed:

in order to prevent misjudge and reduce the detection missing ratio, thefine-leak detection time t₅, which is from putting in the test chamberto beginning to read the argon measured leak rate R_(Ar) of fine-leak,is no less than the minimum fine-leak detection time t_(5min) and nolonger than t_(5max) designed in step S2.5; t_(5min) is the longest timefor the background helium leak rate reducing to ⅓R_(max) (includingR_(2max), R_(1max), R_(2n.max) and R_(1n.max)) in the condition ofstable test system and empty chamber; and

if the measured helium leak rate R (R can be R₂, R₁, R_(2n), or R_(1n))is higher than R_(max), the component is refused, else the component isaccepted and the further detection is done as described in step S9.

In particular, in step S10, the quantitative detection method isdesigned:

if the quantitative detection τ_(He) or L of is required, the specificmethod of flexible scheme, higher τ_(Hemin) and available lowerR_(Ar0max) is selected in step S1; helium-argon prefilling method orhelium-argon pressuring method after argon prefilling can be selectedfor the first test, then helium-argon pressuring method afterhelium-argon prefilling or helium-argon multi-pressuring method afterargon prefilling can be selected for the repetitive tests.

According to a certain cavity volume V, the flexible scheme is designedin step S2.6; where the ratio k is equal to 0.21 for helium-argonprefilling method, the ith helium-argon pressuring time t_(1i) and themaximum detection-waiting time t_(max) (including t_(3max), t_(2max),t_(3n.max), t_(2n.max)) are shorter than 0.1τ_(Hemin). Thus, the heliummeasured leak rate criterion R_(max) (including R_(2max), R_(1max),R_(2n.max), R_(1n.max)) is given, so as to the relative test conditionof P_(E) (or P_(En)), t_(4max), t_(5max), t_(3min);

in step S8 of fine-leak test, some sample with the same shape, which hasbeen detected and accepted, should be used to prove the absorbed heliumleak rate R_(a)<0.1 R_(max), the background helium measured leak rateR_(b) should be read when the chamber is empty, and the helium measuredleak rate of the component R can be read, which may be R₂, R₁, R_(2n),R_(1n);

for the accepted component (τ_(He)≥τ_(Hemin)), the real helium measuredleak rate R′ (containing R₂′, R₁′, R_(2n)′, R_(1n)′) can be obtained byformula (36),R′=R−R _(b)  (36)

where, R′ contains absorbed helium leak rate and other system deviation,

for the accepted component in hermeticity test, the helium gas exchangeconstant τ_(He) can be approximately obtained by formula (37) throughasymptotic fitting method,

$\begin{matrix}{R_{2}^{\prime} = {\frac{V}{\tau_{He}}\left\lbrack {{{kP}_{0}\mspace{14mu}{\exp\left( {- \frac{t_{3}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\rbrack}} & (37)\end{matrix}$

in the condition of

$t_{3} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}$and kP₀≥10P_(He0), the gas exchange constant τ_(He) can be approximatelyobtained by formula (38),

$\begin{matrix}{\tau_{He} = {\tau_{{He}\mspace{14mu}\min}\frac{R_{2\mspace{14mu}\max}}{R_{2}^{\prime}}}} & (38)\end{matrix}$

for the accepted component in hermeticity test by using helium-argonpressuring method after argon prefilling, the gas exchange constantτ_(He) can be approximately obtained by formula (39) through asymptoticfitting method,

$\begin{matrix}{R_{1}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{{P_{E}\left\lbrack {1 - {\exp\left( {- \frac{t_{1}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\}}} & (39)\end{matrix}$

or it can be obtained by formula (40) in the condition of

${t_{1} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},{t_{2} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},{{P_{E}t_{1}\text{/}T_{He}} \geqslant {10P_{{He}\; 0}}},$

$\begin{matrix}{\tau_{He} = {\tau_{{He}\mspace{14mu}\min}\sqrt{\frac{R_{1\max}}{R_{1}^{\prime}}}}} & (40)\end{matrix}$

for the accepted component in hermeticity test by using helium-argonpressuring method after helium-argon prefilling, τ_(He) can beapproximately obtained by formula (41) through asymptotic fittingmethod,

$\begin{matrix}{R_{2n}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0n}}{\tau_{He}}} \right)}} + {\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{He}}} \right)}}}} \right\}{\exp\left( {- \frac{t_{2n}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\}}} & (41)\end{matrix}$

for the accepted component in hermeticity test by using helium-argonmulti-pressuring method after argon prefilling, τ_(He) can beapproximately obtained by formula (42) through asymptotic fittingmethod,

$\begin{matrix}{R_{1n}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{He}}} \right)}{\exp\left( {- \frac{t_{2n}}{\tau_{He}}} \right)}}} + P_{{He}\; 0}} \right\}}} & (42)\end{matrix}$

then the equivalent standard leak rate L can be obtained by formula (43)when τ_(He) has been gotten,

$\begin{matrix}{L = {\frac{{VP}_{0}}{\tau_{He}}\sqrt{\frac{M_{He}}{M_{A}}}}} & (43)\end{matrix}$

both of τ_(He) and L can be the quantitative detection results withcertain detection deviation

In this invention of the combination test method by using argon asgross-leak tracer gas and using helium as fine-leak tracer gas,helium-argon prefilling method or helium-argon pressuring method afterargon prefilling can be selected for the first test, and helium-argonpressuring method after helium-argon prefilling or helium-argonmulti-pressuring method after argon prefilling can be selected for therepetitive tests; this invention extends the range of argon measuredleak rate criterion R_(Ar0max) for gross-leak test; in order to reducethe leak detection missing rate in fine/gross-leak test and preventmisjudge, this invention extends the maximum detection-waiting time,rules the longest and shortest detection time of fine-leak test andgross-leak test, rules the minimum detection-waiting time forhelium-argon prefilling method, and improves the quantitative detectionmethod. In this way, the applicable range of rigor grade τ_(Hemin) andcavity volume V is further extended, the detection missing offine/gross-leak test can be fundamentally prevented, and furthereffectively improved the feasibility and credibility of the detection.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in FIG. 1, the technical solutions of the present invention arefurther described by detailed description of the embodiments as follows.

1. The Related Terms, Symbols and Definitions

The equivalent standard leak rate L refers to a flow rate of air with atemperature of 25° C.±5° C. and a dew point lower than −25° C. thatpasses through a leak aperture according to a molecular flow modelprovided that air is composed of molecules of a single type, where thepressure at an entrance of the leak aperture is 101.3 kPa and thepressure at an exit of the leak aperture is lower than 1 kPa. Theequivalent standard leak rate is a virtual equivalent, and also referredto as an air standard leak rate.

The helium standard leak rate L_(He) refers to a flow rate of helium gaswith a temperature of 25° C.±5° C. that passes through a leak apertureaccording to a molecular flow model, where the pressure of the heliumgas at an entrance of the leak aperture is standard atmospheric pressureP₀, i.e., 101.3 kPa, and the pressure of the helium gas at an exit ofthe leak aperture is lower than 1 kPa. The standard leak rate of any gasis inversely proportional to the square root of a molecular weight ofthe gas in grams as follows:

$L_{He} = {\sqrt{\frac{M_{A}}{M_{He}}}L}$

where, M_(A) denotes the mean molecular weight of air in grams,M_(A)=28.96 g; and M_(He) denotes the molecular weight of helium gas ingrams, M_(He)=4.003 g.

The fine-leak test refers to hermeticity test on a sealed component withan equivalent standard leak rate L no larger than 1.0 Pa·cm³/s.

The gross-leak test refers to hermeticity test on a sealed componentwith an equivalent standard leak rate L no less than 0.1 Pa·cm³/s, 0.3Pa·cm³/s, 1.0 Pa·cm³/s or 3.0 Pa·cm³/s, which is equivalent with ameasured leak rate R_(Ar0) of gross-leak test by using argon as tracergas no less than 7.95×10⁻³ Pa·cm³/s, 2.39×10⁻³ Pa·cm³/s, 7.95×10⁻³Pa·cm³/s or 2.39×10⁻³ Pa·cm³/s.

The minimum detectable leak rate L₀ for gross-leak test refers to argonmeasured leak rate criterion R_(Ar0max) for gross-leak test, whichensuring the minimum detectable equivalent standard leak rate.

$L_{0} = {R_{{Ar}\mspace{14mu} 0\mspace{14mu}\max}\frac{P_{0}}{P_{{Ar}\; 0}}\sqrt{\frac{M_{Ar}}{M_{A}}}}$

Where, R_(Ar0max) denotes the argon measured leak rate criterion;P_(Ar0) denotes the argon partial pressure in normal air, P_(Ar0)=946Pa; M_(Ar) denotes the molecular weight of argon gas in grams,M_(Ar)=39.948 g.

The equivalent helium measured leak rate of gross-leak test R_(0max)refers to R_(Ar0max) to ensure the detectable helium measured leak rate,which can be obtained as follows:

$R_{0\;\max} = {R_{{Ar}\; 0\max}\frac{P_{{He}\; 0}}{P_{{Ar}\; 0}}\sqrt{\frac{M_{Ar}}{M_{He}}}}$

Where, P_(He0) is the helium partial pressure in normal air,P_(He0)=0.533 Pa.

The helium gas exchange time constant τ_(He) refers to the time neededwhen the internal helium gas pressure of a vacuum sealed component in ahelium gas environment reaches (1-1/e), i.e., 63.2%, of theenvironmental helium gas pressure.

$\tau_{He} = {\frac{{VP}_{0}}{L_{He}} = {\frac{{VP}_{0}}{L}\sqrt{\frac{M_{He}}{M_{A}}}}}$

Where, V denotes a cavity volume of a sealed component.

The helium gas exchange time constant τ_(He0) for gross-leak test refersto the helium gas exchange time constant corresponding to the minimumdetectable leak rate L₀ of gross-leak test.

$\tau_{{He}\; 0} = {\frac{{VP}_{0}}{L_{0}}\sqrt{\frac{M_{He}}{M_{A}}}}$

Where, L₀ is the minimum detectable leak rate for gross-leak test.

The argon gas exchange time constant τ_(Ar0) for gross-leak test refersto the argon gas exchange time constant corresponding to the minimumdetectable leak rate L₀ of gross-leak test.

$\tau_{{Ar}\; 0} = {{\frac{{VP}_{0}}{L_{0}}\sqrt{\frac{M_{Ar}}{M_{A}}}} = \frac{{VP}_{{Ar}\; 0}}{L_{{Ar}\; 0\;\max}}}$

The helium gas exchange time constant τ_(He0.m) for medium leak testrefers to the helium gas exchange time constant corresponding to thevacuum helium leak rate R_(max) when the helium measured leak ratecriterion R_(max) is lower than R_(0max) and the internal helium partialpressure is P_(He0).

$\tau_{{He}\; 0.m} = {\tau_{{He}\; 0}\frac{R_{0\;\max}}{R_{\max}}s}$

The rigor grade τ_(Hemin) refers to a constant of the allowable minimumhelium gas exchange time for an acceptable component under test.

The helium-argon prefilling method: it refers to a cumulative heliummass spectrometric combination test by using argon as tracer gas forgross-leak test and using helium as tracer gas for fine-leak test, andit is applied in the first leak test of the component under test whichhas been prefilled nitrogen with specified ratios of helium gas andargon gas before sealing.

The helium-argon pressuring method after argon prefilling refers to acumulative helium mass spectrometric combination test by using argon astracer gas for gross-leak test and using helium as tracer gas forfine-leak test, and it is applied in the first leak test of thecomponent under test which has been prefilled nitrogen with specifiedratios of argon gas and pressured a certain partial pressure of heliumand argon for some time after sealing.

The helium-argon pressuring method after helium-argon prefilling refersto a cumulative helium mass spectrometric combination test by usingargon as tracer gas for gross-leak test and using helium as tracer gasfor fine-leak test, and it is applied in the repetitive tests of thecomponent under test which has been prefilled nitrogen with specifiedratios of helium-argon gas and pressured a certain partial pressure ofhelium and argon for some time after sealing.

The helium-argon multi-pressuring method after argon prefilling refersto a cumulative helium mass spectrometric combination test by usingargon as tracer gas for gross-leak test and using helium as tracer gasfor fine-leak test, and it is applied in the repetitive tests of thecomponent under test which has been prefilled nitrogen with specifiedratios of argon gas and pressured a certain partial pressure of heliumand argon for some time after sealing.

The fixed scheme of helium-argon prefilling method and helium-argonpressuring method after argon prefilling for the first time refers to atest scheme that ruling the parameters according to the selected rigorgrade, test method, and argon measured leak rate criterion forgross-leak test. The parameters contains the cavity volume segments, thefixed condition of helium-argon prefilling or helium-argon pressuringafter argon prefilling, the helium measured leak rate criterion forfine-leak test, the detection-waiting time, the longest gross-leakdetection time and fine-leak detection time. The fixed scheme isconvenient and easy to operate but is accompanied with a certain testdeviation.

The flexible scheme of helium-argon prefilling method and helium-argonpressuring method after argon prefilling for the initial test orhelium-argon pressuring method after helium-argon prefilling andhelium-argon multi-pressuring method after argon prefilling for therepetitive tests: it refers to a test scheme that ruling the parametersaccording to the selected rigor grade, test method, and argon measuredleak rate criterion for gross-leak test. For a certain cavity volume,the parameters contains the fixed ratio of argon when sealing, flexibleratio of helium when helium-argon pressuring, flexible helium measuredleak rate criterion for fine-leak test, the maximum and minimumdetection-waiting time, the longest gross-leak detection time andfine-leak detection time. The flexible scheme can be used for moreaccurate test, but involves flexible and specific design and calculationof the test condition and the criterion for measured leak rate.

2. Instruments, Tool Sets and the Component Under Test

The needed test instruments and tool sets for the method of cumulativehelium mass spectrometric combination test by using argon as gross-leaktracer gas and using helium as fine-leak tracer gas mainly include: ahelium-argon prefilling and sealing device, a helium-argon pressuringtank, a detecting chamber, a standard aperture, a cumulative helium massspectrometric combination leak detector, etc.

The helium-argon prefilling and sealing device should meet the followingrequirements that: the pressure of prefilled gas is 1.00˜1.10 standardatmospheric pressure P₀; the device can be vacuumed to below 10 Pa; thedevice can be prefilled with a gas mixture of nitrogen, helium andargon, wherein the ratio of the partial pressure of argon gas to thetotal pressure is 0.934%, the ratio of the partial pressure of heliumgas to the total pressure is 21.0% or 3%˜50% and the rest is nitrogen.The ratios of argon gas and helium gas are not deviated by more than±5%; and the component is sealed in the prefilled gas.

The helium-argon pressurizing tank should meet the followingrequirements of: a sustainable internal pressure with an absolutepressure of the total pressure for helium-argon pressuring and asustainable external pressure with an absolute pressure of the standardatmospheric pressure; the tank can be vacuumed to below 10 Pa; in thepressured gas, the partial pressure of argon gas P_(Ar0)=946 Pa and thepartial pressure of helium gas is designed P_(E.n). Neither P_(E.n) norP_(Ar0) are deviated by more than ±5%; and a pressure drop in 40 hoursless than 10% of the initial pressure inside the tank which is thehighest pressure of helium pressuring.

The detecting chamber should meet the following requirements that: itseffective capacity meeting the leak test requirements shall be as smallas possible, and the net volume of the detecting chamber after puttinginto a component under test is no more than 50 times of the cavityvolume V of the component under test; the chamber can be vacuumed tobelow 5 Pa after being closed; and a standard leak aperture should beable to be put into the chamber or be connected to the chamber in theshortest distance.

The standard leak aperture should meet the following requirements that:the measurable leak rate range that can be calibrated and covered by thenominal value of the leak rate of the helium and argon standard apertureshould meet the argon gas gross-leak and helium gas fine-leak testrequirements; and the standard leak aperture should be used in thecalibration or verification validity period.

During cumulative helium mass spectrometric gross-leak and fine-leakcombination test, the cumulative helium mass spectrometric combinationleak detector should meet the corresponding standards and therequirements of the present test method. The helium mass spectrometricleak test system which is connected to the detecting chamber should meetthe following requirements:

a normal maintenance procedure should be carried out on the leak testsystem according to a maintenance regime. The detector should work in aclean indoor environment with a temperature of 25⁻⁵ ⁺³° C., a relativehumidity no more than 50% and without an argon gas and helium gascontamination;

having the function of using argon gas as tracer gas of gross-leak test,the gross-leak test can be carried out via cumulating the leakage ofargon gas or not, but the test gas channel should not be connected tothe cryogenic pump; Having the function of using helium gas as tracergas of fine-leak test, the test gas of fine-leak test can be carried outby cumulating via the cryogenic pump or be carried out without thecryogenic pump and cumulating;

the leak test system is started and working parameters of the leakdetector are adjusted, so that the leak detector is warmed and works fora period of time, and a specified verification method is employed toverify that the leak test system is in a stable working state. In thestable working state, the stable background value of argon measured leakrate R_(Arb) of the leak detector during the load-free test should be nolarger than ⅓ of the criterion for argon measured leak rate R_(Ar0max)of gross-leak test, and the stable background value of helium leak rateR_(b) of fine-leak test should be no larger than ⅓ of the criterion forhelium measured leak rate R_(max) of fine-leak test;

the system can provided with the relation curve between argon measuredleak rate and time for gross-leak test started from flushing duringgross-leak test and can determine whether to carry out the cumulativegross-leak test or not, the argon measured leak rate criterion forgross-leak test R_(Ar0max), the minimum gross-leak detection timet_(4min), the maximum gross-leak detection time t_(4max), and gross-leakdetection time t₄;

the system can provided with the relation curve between helium measuredleak rate and time for fine-leak test during fine-leak test and candetermine whether to carry out the cumulative fine-leak test or not, thecriterion for helium measured leak rate R_(max), the minimum fine-leakdetection time t_(5min), the maximum fine-leak detection time t_(5max),and fine-leak detection time t₅;

when needed, after stabilizing the system again, the leak test systemshall be verified whether it is in a stable working state by employing aspecified verification method, and then other component is thendetected; and

the vacuumed detecting chamber is filled with gas, preferably with aclean nitrogen gas, so as to alleviate the contamination of the heliumgas and argon gas in the leak test system.

The component under test should meet the following requirements:

the welding material structure and the surface conditions of the weldingseam, the metal, the glass and the ceramic of the component under testshould be controlled, and fingerprints, welding flux and organicmaterials on the surface thereof should be reduced or eliminated, toavoid excessive helium gas and argon gas absorbed on the surface duringhelium-argon prefilling, argon prefilling, helium-argon pressuring andstoring;

measures shall be taken to ensure that no unstable leak aperture or seamand sub-cavity outside a sealing nugget ring exist on the componentunder test;

the mixed nitrogen-helium-argon or nitrogen-argon gas prefilled and thehelium-argon gas pressured when the component under test is sealedshould be dry and clean; and

after sealing with helium-argon or argon prefilling or helium-argonpressuring, the component under test should be preserved in a dry andclean air environment with a normal helium and argon gas content,without being contaminated, to alleviate the contamination of the heliummass spectrometric leak test system and prevent a leak aperture frombeing blocked.

During the working process, the following safety regulations shall befollowed:

the gas cylinders of the nitrogen gas, the helium gas and the argon gasshould conform to the safety laws and standards; the helium-argonpressurizing tank and the connection pipes pass through a strength testin a condition of 1.5 times of the pressure of pressurized gas; thepressure applied should not be higher than the sustainable pressure of acomponent under test; and the pressurizing and discharging rate of thehelium-argon pressurizing tank is controlled, so that both thepressurizing time and the discharging time for reaching a test pressureshould be no less than 20 s.

3. Embodiments Preferred Embodiment 1

The present invention provides a combination test method by using argonas gross-leak tracer gas and using helium as fine-leak tracer gas, whichimproved the existed test method of cumulative helium mass spectrometriccombination test by using argon gas as gross-leak tracer gas and usinghelium gas as fine-leak tracer gas. The working procedure thereof is asfollows.

Step S1 of Selecting:

according to basic criterions—the rigor grade τ_(Hemin), the helium andargon leak rate range of the Cumulative Helium Leak Detector (CHLD), thehelium and argon background leak rate, the history of leak test, cavityvolume of the component under test, and the absorbed helium and argonleak rate after its removal, the fixed or flexible scheme ofhelium-argon prefilling method and helium-argon pressuring method afterargon prefilling are selected for the first hermeticity test, flexiblescheme of helium-argon pressuring method after helium-argon prefillingor helium-argon multi-pressuring method after argon prefilling isselected for repetitive hermeticity test, and the argon measured leakrate criterion R_(Ar0max) is selected for gross-leak test;

the rigor grade τ_(Hemin) is specified by the product specifications andthe contract. When the hermeticity requirements of the productspecifications or the contract is an equivalent standard leak ratecriterion L_(max), τ_(Hemin) is obtained by formula (35). The value ofτ_(Hemin) would be 20 days, 200 days, or 2000 days for the fixed schemeand for the flexible scheme the value can be same as the fixed scheme orbe flexibly selected;

for the first test, the helium-argon prefilling method would begenerally selected for its high sensitivity and larger range ofavailable τ_(Hemin) and cavity volume, and it's better to selecthelium-argon pressuring method after argon prefilling when the componenthas larger cavity volume and the rigor grade τ_(Hemin) is lower;excepted some high accurate test for several samples, generally thefixed scheme which is easy to operate but is accompanied with a certaintest deviation is selected; the flexible scheme which can be used formore accurate test, but involves flexible and specific design andcalculation of the test condition and the criterion for measured leakrate may also be selected as well;

for the repetitive tests, the flexible scheme of helium-argon pressuringmethod after helium-argon prefilling is selected if the first test usedhelium-argon prefilling method; and the flexible scheme of helium-argonmulti-pressuring method after argon prefilling is selected if the firsttest used helium-argon pressuring method after argon prefilling;

for the fixed scheme, as shown in Table 1 and Table 2, according to thecavity volume V of a component under test, on a precondition thatR_(Armax) is larger than 3 times of the surface absorbed argon leak rateR_(Ara) of the component under test in dry air, R_(Ar0max) is selectedas the value of 7.95×10⁻⁴ Pa·cm³/s, 2.39×10⁻³ Pa·cm³/s, 7.95×10⁻³Pa·cm³/s or 2.39×10⁻² Pa·cm³/s; For the flexible scheme, according tothe absorbed argon leak rate R_(Ara), R_(Ar0max) can be selected fromthe values above or selected flexibly.

Step S2 of Designing:

according to the test method, the scheme, τ_(Hemin) and R_(Ar0max) whichis selected in step S1, the pressure and time conditions of helium-argonprefilling, argon prefilling, or helium-argon pressuring are designed instep S2.1; the helium measured leak rate criterion R_(max) is designedin step S2.2 and the maximum detection-waiting time t_(max) is designedin step S2.4; the maximum gross-leak detection time t_(4max), themaximum fine-leak detection time t_(5max), and the minimumdetection-waiting time t_(3min) of helium-argon prefilling method aredesigned in step S2.5; and the fixed scheme or flexible scheme isdesigned in step S2.6;

in step S2.1, the pressure and time conditions of helium-argonprefilling, argon prefilling or helium-argon pressuring are designed:

if the helium-argon prefilling method is selected in the firstdetection, the total gas pressure P is (1+10%)P₀ during seal, withhelium partial pressure P_(He) of (1+10%)kP₀, argon partial pressureP_(Ar) of (1+10%) P_(Ar0), and the rest of nitrogen, where P₀ isstandard atmospheric pressure 1.013×10⁵ Pa; k is the helium prefillingratio P_(Hed)/P₀, wherein P_(Hed) is a helium partial pressure of adesigned helium-argon prefilling when the total pre-inflation pressureis standard atmospheric pressure; P_(Ar0) is the normal partial pressureof argon in atmosphere;

for the fixed scheme, k=0.21 is chosen; and k is variable from 0.03 to0.5 for flexible scheme;

if helium-argon pressuring method after argon prefilling is selected forthe first detection, the total gas pressure P is (1+10%)P₀ during seal,with argon partial pressure (1+10%) P_(Ar0) and the rest of nitrogen;the total pressure of bombed gas is no more than 6P₀, in which there isargon with the partial pressure P_(Ar) equal to P_(Ar0), helium with thepartial pressure P_(E) no less than 2P₀. The helium-argon pressuringtime t₁ is long enough to make sure that the helium measured leak ratecriterion R_(1max) reaches the detectable range of detectors;

for the repetitive tests, if the helium-argon pressuring method afterhelium-argon prefilling is selected, in the nth (n is no less than 1)helium-argon pressuring, the argon partial pressure P_(Ar) is P_(Ar0),the helium partial pressure P_(En) is no less than 2P₀ to prevent thefine-leak detection missing; the helium-argon pressuring time tin can beobtained by formula (1),

$\begin{matrix}\left. \begin{matrix}{t_{1\; n} \geqslant {\frac{1}{P_{En}}\left( {{\frac{1}{10\; e}{kP}_{0}t_{3.0\; n}} + {0.15{\sum\limits_{i = 1}^{n - 1}\;{P_{Ei}t_{1\; i}}}}} \right)}} \\{t_{1\; n} \geqslant {1.2\mspace{14mu} h}}\end{matrix} \right\} & (1)\end{matrix}$

where, t_(3.0n) is the interval time from the ending of sealing to theending of the nth helium-argon pressuring; P_(E); and t_(1i) are thehelium part pressure and time in the ith helium-argon pressuring; and

for the repetitive tests, if the helium-argon multi-pressuring methodafter argon prefilling is selected, in the nth (n is no less than 2)helium-argon pressuring, the argon partial pressure P_(Ar) is P_(Ar0),the helium partial pressure P_(En) is no less than 2P₀ to prevent thefine-leak detection missing; the helium-argon pressuring time tin isobtained by formula (1) when k=0.

In step S2.2, the helium measured leak rate criterion R_(max) offine-leak test is designed:

for the helium-argon prefilling method in first test, when thecomponents under detection are stored for the detection-waiting time t₃in the normal atmosphere, the helium measured leak rate criterionR_(2max) of the fine-leak test can be obtained by formula (2),

$\begin{matrix}{R_{2\max} = {\frac{{VkP}_{0}}{\tau_{{He}\mspace{14mu} m\; i\; n}}{\exp\left( {- \frac{t_{3}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}}} & (2)\end{matrix}$

where V denotes a internal cavity volume of the component underdetection;

R_(2max) can be obtained by approximate formula (3) in the condition of

${t_{3} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}}},$

$\begin{matrix}{R_{2\max} = \frac{{VkP}_{0}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} & (3)\end{matrix}$

for the helium-argon pressuring method after argon prefilling in thefirst test, the components under detection are stored in air after seal,bombed helium-argon for time t₁ and then stored for detection-waitingtime t₂, the helium measured leak rate criterion R_(2max) of thefine-leak test can be obtained by formula (4),

$\begin{matrix}{R_{1\max} = {{\frac{{VP}_{E}}{\tau_{{He}\mspace{14mu} m\; i\; n}}\left\lbrack {1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}}} & (4)\end{matrix}$

or R_(1max) is obtained by approximate formula (5) in the condition of

$t_{1} \leqslant {\frac{1}{5}\tau_{{He}\mspace{11mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{2}} \leqslant {\frac{1}{10}{\tau_{{He}\mspace{11mu}\min}.}}$

$\begin{matrix}{R_{1\;\max} = \frac{{VP}_{E}t_{1}}{\tau_{{He}\mspace{14mu} m\; i\; n}^{2}}} & (5)\end{matrix}$

for the helium-argon pressuring method after helium-argon prefilling inthe repetitive tests, the helium measured leak rate criterion R_(2n.max)of fine-leak test after the nth (n is no less than 1) helium-argonpressuring can be obtained by formula (6),

$\begin{matrix}{R_{2\;{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu} m\; i\; n}}\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0\; n}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} + {\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1\; i}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2,{in}}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}}}} \right\}{\exp\left( {- \frac{t_{2\; n}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}}} & (6)\end{matrix}$

where t_(2.in) is the interval time from the ending of the ithhelium-argon pressuring to the ending of nth helium-argon pressuring;

similarly, R_(2n.max) can be obtained by approximate formula (7) in thecondition of

${t_{1\; i} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu} m\; i\; n}}},{t_{2\; n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}}},$

$\begin{matrix}{R_{2\;{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu} m\; i\; n}}\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0\; n}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} + {\frac{1}{\tau_{{He}\mspace{14mu} m\; i\; n}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1\; i}{\exp\left( {- \frac{t_{2,{in}}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}}}}} \right\}}} & (7)\end{matrix}$

for the repetitive tests, in the condition of

${t_{3.0\; n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}\mspace{14mu}{and}\mspace{14mu} t_{2\; n}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}}},$R_(2n.max) can also be obtained by approximate formula (8),

$\begin{matrix}{R_{2\;{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu} m\; i\; n}}\left( {{kP}_{0} + {\frac{1}{\tau_{{He}\mspace{14mu} m\; i\; n}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1\; i}}}}} \right)}} & (8)\end{matrix}$

furthermore, when

$\left( {\frac{1}{\tau_{{He}\mspace{11mu}\min}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}}}} \right) \leqslant {\frac{1}{10}{kP}_{0}}$in the formula (8), R_(2n.max) can be obtained by formula (9),

$\begin{matrix}{R_{2{n.\max}} = \frac{{VkP}_{0}}{\tau_{{He}\mspace{11mu}\min}}} & (9)\end{matrix}$

for the helium-argon multi-pressuring method after argon prefilling inthe repetitive tests, the helium measured leak rate criterion R_(1n.max)of fine-leak test after the nth (n is no less than 2) helium-argonpressuring can be obtained by formula (10),

$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{11mu}\min}}\left\{ {\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{{He}\mspace{11mu}\min}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.i\; n}}{\tau_{{He}\mspace{11mu}\min}}} \right)}}} \right\}{\exp\left( {- \frac{t_{2n}}{\tau_{{He}\mspace{11mu}\min}}} \right)}}} & (10)\end{matrix}$

or, R_(1n.max) can be obtained by approximate formula (11) in thecondition of

${t_{1i} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu}\min}}},{t_{2n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$

$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}^{2}}\left\lbrack {\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}{\exp\left( {- \frac{t_{2.i\; n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} \right\rbrack}} & (11)\end{matrix}$

furthermore, when

$t_{2.i\; n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{1i}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}$in formula (11), R_(1n.max) can be obtained by formula (12).

$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}^{2}}{\sum\limits_{i = 1}^{n}\;{P_{Ei}t_{1i}}}}} & (12)\end{matrix}$

In step S2.3, the upper limit of the cavity volume can be obtained byformula (13),

$\begin{matrix}{V_{\max} = {\frac{L_{\max\mspace{11mu} 0}\tau_{{He}\mspace{14mu}\min}}{P_{0}}\sqrt{\frac{M_{A}}{M_{He}}}}} & (13)\end{matrix}$

where L_(max0) is the maximum detectable equivalent standard leak rate,L_(max0)=1.0 Pa·cm³/s; M_(He) is the molecular weight of helium ingrams, M_(He)=4.003 g; M_(A) is the mean molecular weight of air ingrams, M_(A)=28.96 g.

In step S2.4, the maximum detection-waiting time t_(max) of fine-leaktest is designed:

corresponding to the argon measured leak rate criterion R_(Ar0max) ofgross-leak test, R_(0max), which is the helium measured leak ratecriterion of gross-leak test when the helium partial pressure P_(He) isequal to P_(He0) in the component under test, can be obtained by formula(14),

$\begin{matrix}{R_{0\mspace{11mu}\max} = {R_{{Ar}\mspace{11mu} 0\mspace{11mu}\max}\frac{P_{{He}\mspace{11mu} 0}}{P_{{Ar}\mspace{11mu} 0}}\sqrt{\frac{M_{Ar}}{M_{He}}}}} & (14)\end{matrix}$

where P_(He0) is the helium partial pressure in normal atmosphere,P_(He0)=0.533 Pa; P_(Ar0) is the argon partial pressure in normalatmosphere, P_(Ar0)=946 Pa; M_(Ar) is the molecular weight of argon ingrams, M_(Ar)=39.948 g;

the helium exchange time constant τ_(He0) of gross-leak can be obtainedby formula (15),

$\begin{matrix}{\tau_{{He}\mspace{11mu} 0} = {{\frac{{VP}_{0}}{L_{0}}\sqrt{\frac{M_{He}}{M_{A}}}} = {\frac{{VP}_{{He}\mspace{11mu} 0}}{R_{0\mspace{11mu}\max}} = {\frac{{VP}_{{Ar}\mspace{11mu} 0}}{R_{{Ar}\mspace{11mu} 0\mspace{11mu}\max}}\sqrt{\frac{M_{He}}{M_{Ar}}}}}}} & (15)\end{matrix}$

where L₀ is the minimum detectable equivalent standard leak rate ofgross-leak,

${L_{0} = {R_{{Ar}\mspace{11mu} 0\mspace{11mu}\max}\frac{P_{0}}{P_{{Ar}\; 0}}\sqrt{\frac{M_{Ar}}{M_{A}}}}};$

the argon exchange time constant τ_(Ar0) of gross-leak can be obtainedby formula (16),

$\begin{matrix}{\tau_{{Ar}\mspace{11mu} 0} = {\frac{{VP}_{{Ar}\mspace{11mu} 0}}{R_{{Ar}\mspace{11mu} 0\mspace{11mu}\max}} = {\tau_{{He}\mspace{11mu} 0}\sqrt{\frac{M_{Ar}}{M_{He}}}}}} & (16)\end{matrix}$

the helium exchange time constant τ_(He0.m) of medium-leak can beobtained by formula (17),

$\begin{matrix}{\tau_{{He}\mspace{11mu} 0.m} = {\tau_{{He}\mspace{11mu} 0}\frac{R_{0\mspace{11mu}\max}}{R_{\max}}}} & (17)\end{matrix}$

where the fine-leak helium measured leak rate criterion R_(max) is lessthan R_(0max);

for helium-argon prefilling method, when τ_(Hemin)>τ_(He0) andR_(2max)≥R_(0max), the maximum detection-waiting time of fine-leak testor combination test t_(3max) can be obtained by formula (18),

$\begin{matrix}{t_{3\mspace{11mu}\max} = {{\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\mspace{11mu} 0}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0}} \right)}} = {\frac{\tau_{{He}\mspace{11mu}\min}{VP}_{{He}\mspace{11mu} 0}}{{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}} - {VP}_{{He}\mspace{11mu} 0}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}}{{VP}_{{He}\mspace{11mu} 0}} \right)}}}} & (18)\end{matrix}$

for the fixed scheme, t_(3max) can be obtained by formula (19),

$\begin{matrix}\left. \begin{matrix}{t_{3\;\max} = {\frac{\tau_{{He}\mspace{11mu}\min}{VP}_{{He}\; 0}}{{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}} - {VP}_{{He}\mspace{11mu} 0}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}}{{VP}_{{He}\mspace{11mu} 0}} \right)}}} \\{t_{3\;\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}}\end{matrix} \right\} & (19)\end{matrix}$

for the helium-argon prefilling method, when τ_(Hemin)>τ_(He0) andR_(2max)<R_(0max), t_(3max) can be obtained by formula (20),

$\begin{matrix}{t_{3\;\max} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\; 0.m}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\; 0.m}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\; 0.m}} \right)}}} & (20)\end{matrix}$

for the fixed scheme, t_(3max) can be obtained by formula (21),

$\begin{matrix}\left. \begin{matrix}{t_{3\;\max} = {\frac{\tau_{{He}\mspace{11mu}\min}P_{{He}\mspace{11mu} 0}}{{kP}_{0} - P_{{He}\; 0}}{\ln\left( \frac{{kP}_{0}}{P_{{He}\; 0}} \right)}}} \\{t_{3\;\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}}\end{matrix} \right\} & (21)\end{matrix}$

for the helium-argon pressuring method after argon prefilling, whenτ_(Hemin)>τ_(He0) and R_(1max)≥R_(0max), the maximum detection-waitingtime of fine-leak test t_(2max) can be obtained by formula (22),

$\begin{matrix}\begin{matrix}{t_{2\;\max} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{{He}\mspace{11mu} 0}\;}}\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu} 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu}\min}}} \right)}} \right\rbrack}} \right\}}} \\{= \frac{\tau_{{He}\mspace{11mu}\min}{VP}_{{He}\mspace{11mu} 0}}{{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}} - {VP}_{{He}\mspace{11mu} 0}}} \\{\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}}{{VP}_{{He}\mspace{11mu} 0}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}R_{0\mspace{11mu}\max}}{{VP}_{{He}\mspace{11mu} 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu}\min}}} \right)}} \right\rbrack}} \right\}}\end{matrix} & (22)\end{matrix}$

for the fixed scheme, t_(2max) can be obtained by formula (23),

$\begin{matrix}\left. \begin{matrix}{t_{2\;\max} = {\frac{\tau_{{He}\mspace{11mu}\min}{VP}_{{He}\mspace{11mu} 0}}{{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}} - {VP}_{{He}\mspace{11mu} 0}}\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}R_{0\mspace{11mu}\max}}{{VP}_{{He}\mspace{11mu} 0}} \right)} +} \right.}} \\\left. {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}R_{0\mspace{11mu}\max}}{{VP}_{{He}\mspace{11mu} 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu}\min}}} \right)}} \right\rbrack} \right\} \\{t_{2\;\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}}\end{matrix} \right\} & (23)\end{matrix}$

for the helium-argon pressuring method after argon prefilling, whenτ_(Hemin)>τ_(He0), R_(1max)<R_(0max), t_(2max) can be obtained byformula (24),

$\begin{matrix}{t_{2\;\max} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0.m}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\mspace{11mu} 0.m}}\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0.m}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu} 0.m}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu}\min}}} \right)}} \right\rbrack}} \right\}}} & (24)\end{matrix}$

for the fixed scheme, t_(2max) can be obtained by formula (25),

$\begin{matrix}\left. \begin{matrix}{t_{2\mspace{11mu}\max} = {\frac{\tau_{{He}\mspace{11mu}\min}^{2}P_{{He}\mspace{11mu} 0}}{{P_{E}t_{1}} - {P_{{He}\mspace{11mu} 0}\tau_{{He}\mspace{11mu}\min}}}\left\{ {{\ln\left( \frac{P_{E}t_{1}}{P_{{He}\mspace{11mu} 0}\tau_{{He}\mspace{11mu}\min}} \right)} +} \right.}} \\\left. {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{P_{E}t_{1}^{2}}{P_{{He}\mspace{11mu} 0}\tau_{{He}\mspace{11mu}\min}^{2}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu}\min}}} \right)}} \right\rbrack} \right\} \\{t_{2\mspace{11mu}\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}}\end{matrix} \right\} & (25)\end{matrix}$

for the helium-argon pressuring method after helium-argon prefilling,after the nth (n is no less than 1) helium-argon pressuring, the maximumdetection-waiting time can be obtained by formula (26) whenτ_(Hemin)>τ_(He0) and R_(2n.max)≥R_(0max),

$\begin{matrix}{t_{3{n.\max}} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\mspace{11mu} 0}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0}} \right)}}} & (26)\end{matrix}$

in the condition of τ_(Hemin)>τ_(He0) and R_(2n.max)<R_(0max),t_(3n.max) can be obtained by formula (27),

$\begin{matrix}{t_{3{n.\max}} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0.m}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\mspace{11mu} 0.m}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0.m}} \right)}}} & (27)\end{matrix}$

for the helium-argon multi-pressuring method after argon prefilling,after the nth (n is no less than 2) helium-argon pressuring, the maximumdetection-waiting time of fine-leak t_(2n.max) can be obtained byformula (28), when τ_(Hemin)>τ_(He0) and R_(1n.max)≥R_(0max),

$\begin{matrix}{t_{2{n.\max}} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\mspace{11mu} 0}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0}} \right)}}} & (28)\end{matrix}$

in the condition of τ_(Hemin)>τ_(He0) and R_(1n.max)<R_(0max),t_(2n.max) can be obtained by formula (29),

$\begin{matrix}{t_{2{n.\max}} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0.m}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\mspace{11mu} 0.m}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0.m}} \right)}}} & (29)\end{matrix}$

in order to ensure the feasibility of the tests for numbers ofcomponents under test, all the t_(max) above (including t_(3max),t_(2max), t_(3n.max), t_(2n.max)) are no less than 0.5 hour.

In step S2.5, in order to reduce or prevent detection missing ingross-leak test and fine-leak test, the parameters including the maximumgross-leak detection time t_(4max), the maximum fine-leak detection timet_(5max) and the minimum detection-waiting time of helium-argonprefilling method t_(3min) are designed:

t_(4max) can be obtained by formula (30) when using one of the fourtypical hermeticity test methods (including helium-argon prefillingmethod, helium-argon pressuring method after argon prefilling,helium-argon pressuring method after helium-argon prefilling, andhelium-argon multi-pressuring method after argon prefilling),

$\begin{matrix}\left. \begin{matrix}{t_{4\mspace{11mu}\max} = {{\frac{1}{10}\tau_{{Ar}\; 0}} = {\frac{1}{10}\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\; 0\mspace{11mu}\max}}}}} \\{{30\mspace{14mu} s} \leqslant t_{4\;\max} \leqslant {900\mspace{11mu} s}}\end{matrix} \right\} & (30)\end{matrix}$

for the four typical hermeticity test methods, when the measured leakrate criterion of fine-leak test R_(max) (including R_(2max), R_(1max),R_(2n.max), R_(1n.max)) is no less than 0.905R_(0max), t_(5max) can beobtained by formula (31),

$\begin{matrix}\left. \begin{matrix}{t_{5\mspace{11mu}\max} = {{\frac{1}{10}\tau_{{He}\mspace{11mu} 0}} = {\frac{1}{10}\frac{{VP}_{0}}{L_{0}}\sqrt{\frac{M_{He}}{M_{A}}}}}} \\{{60\mspace{14mu} s} \leqslant t_{5\;\max} \leqslant {1200\mspace{11mu} s}}\end{matrix} \right\} & (31)\end{matrix}$

and for helium-argon prefilling method, t_(3min) can be obtained byformula (32),

$\begin{matrix}\left. \begin{matrix}{t_{3\mspace{11mu}\min} = {\tau_{{He}\; 0}\frac{1}{1 + {10\; l_{{He}.n}}}}} \\{t_{3\mspace{11mu}\min} \leqslant {\frac{1}{3}t_{3\mspace{11mu}\max}}} \\{or} \\{t_{3\mspace{11mu}\min} \leqslant {t_{3\mspace{11mu}\max} - {24\mspace{11mu} h}}}\end{matrix} \right\} & (32)\end{matrix}$

where l_(He.n) is the viscous conductance constant corresponding to L₀(Pa·cm³/s), when the pressures of both leak hole ends respectively areP₀ and 0, and can be obtained by formula (33),l _(He.n)=0.5L ₀ ^(0.314)  (33)

for the four typical hermeticity test methods, when R_(max) is less than0.905R_(0max), t_(5max) can be obtained by formula (34),

$\begin{matrix}\left. \begin{matrix}{t_{5\mspace{11mu}\max} = {\frac{{VP}_{{Ar}\mspace{11mu} 0}}{R_{{Ar}\; 0\mspace{11mu}\max}}\sqrt{\frac{M_{He}}{M_{Ar}}}{\ln\left( \frac{R_{0\mspace{11mu}\max}}{R_{\max}} \right)}}} \\{{60\mspace{14mu} s} \leqslant t_{5\;\max} \leqslant {1200\mspace{14mu} s}}\end{matrix} \right\} & (34)\end{matrix}$

In step S2.6, the fixed scheme or flexible scheme is designed:

according to a certain cavity volume V, the selected τ_(Hemin) andR_(Ar0max), the flexible scheme can be designed for the combination testby using argon as gross-leak tracer gas and using helium as fine-leaktracer gas.

for the components under detection with acceptable hermeticity rigorgrade τ_(Hemin), the maximum equivalent standard leak rate L_(max) canbe obtained by formula (35),

$\begin{matrix}{L_{\max} = {\frac{{VP}_{0}}{\tau_{{He}\mspace{11mu}\min}}\sqrt{\frac{M_{He}}{M_{A}}}}} & (35)\end{matrix}$

the range of cavity volume V for 0.0006 cm³˜200 cm³ is divided intodifferent segments, and then the fixed scheme of the helium-argonprefilling method and helium-argon pressuring method after argonprefilling is designed. In the design, R_(2max) can be obtained byformula (3) and R_(1max) by formula (5); the lower limit of a cavityvolume segment will be used when designing R_(2max), R_(1max), t_(3max),t_(2max), t_(4max), t_(5max) and L_(max); similarly, the upper limit ofV will be used when designing t_(3min). The fixed scheme of helium-argonprefilling method is shown in table 1 and helium-argon pressuring methodafter argon prefilling in table 2. Where “/” denotes that the value isnot available.

Step 3 of Helium-Argon Prefilling, Argon Prefilling or Helium-ArgonPressuring:

according to step S2 of designing, it is done that sealing withprefilling gas or helium-argon pressuring. The component under testwhich has not been sealed is placed into the helium-argon prefillingdevice and then the device is vacuumed to below 10 Pa. Argon gas isbombed to reach the pressure (1+10%)946 Pa, helium gas is bombed toreach the pressure (9.34×10⁻³+k)(1+10%)P₀, nitrogen gas to the pressure(1+10%) P₀, and then the components are sealed; for the fixed scheme ofthe helium-argon prefilling method, k=21.0%, and for the flexible schemeof the helium-argon prefilling method, the ratio k can be the value inthe range of 3%˜50%, or preferably the value of 21.0%. For helium-argonpressuring method after argon prefilling, k can be the value zero; k isnot deviated by more than +5%. The prefilled gas for the fixed scheme ofthe helium-argon prefilling method can also employ helium gas accountingfor 21% of the total amount added to nitrogen gas produced with pressureswing adsorption method. Nitrogen gas produced with pressure swingadsorption method by removing oxygen, carbon dioxide, hydrogen, vaporand organic gas in air and reserving nitrogen and argon gas in air;

for the helium-argon pressuring of helium-argon pressuring method afterargon prefilling, helium-argon pressuring method after helium-argonprefilling, and helium-argon multi-pressuring method after argonprefilling, the component under test should be placed in a helium-argonpressuring tank which is vacuumed to below 10 Pa; Within 2 min, argongas of P_(Ar)=946 Pa is filled into primarily and then helium gas isfilled into according to the partial pressure P_(E) or P_(E.n) ofpressured helium gas permitted by S2.1. The total pressure of argon andhelium gas is maintained within time of t₁ or tin. Wherein, P_(E) andP_(E.n) are no less than 2P₀, P_(E), P_(E.n), t₁ and t_(1n) are notdeviated by more than +5%; and

the pressure P_(Ar) of helium-argon prefilling or argon prefilling, thevalue of k and time for sealing should be recorded and reserved; theargon partial pressure P_(Ar) and the helium partial pressure P_(E),P_(E.n), the helium-argon pressuring time t₁ and t_(1n) for eachhelium-argon pressuring, and the ending time of helium-argon pressuringshould be recorded and reserved.

TABLE 1 Fixed scheme of helium-argon prefilling method for thecumulative helium mass spectrometric combination test the rigor gradeT_(Hemin) = 20 d segments of the measured leak rate criterion forgross-leak R_(Ar0max) (Pa · cm³/s) cavity volume 7.95E−4 2.39E−3 7.95E−32.39E−2 V R_(2max) L_(max) t_(3min) t_(3max) t_(4max) t_(5max) t_(3min)t_(3max) t_(4max) t_(5max) t_(3min) t_(3max) t_(4max) t_(5max) t_(3min)t_(3max) t_(4max) t_(5max) cm³ Pa · cm³/s Pa · cm³/s h h s s h h s s h hs s h h s s 0.002~<0.006 2.46E−5 4.36E−5  1.83E−1 1.62E0 2.38E2 7.53E1 // / / / / / / / / / / 0.006~<0.02  7.39E−5 1.31E−4  6.10E−1 4.16E07.14E2 2.26E2  1.57E−1 1.62E0 2.37E2 7.53E1 / / / / / / / / 0.02~<0.062.46E−4 4.36E−4 1.83E0 1.14E1 9.00E2 7.53E2  4.72E−1 4.55E0 7.92E22.51E2  1.05E−1 1.62E0 2.37E2 7.53E1 / / / / 0.06~<0.2  7.39E−4 1.31E−36.10E0 2.75E1 9.00E2 1.20E3 1.57E0 1.14E1 9.00E2 7.53E2  3.49E−1 4.16E07.14E0 2.26E2 8.65E−2 1.62E0 2.37E2 7.53E1 0.2~<0.6 2.46E−3 4.36E−31.83E1 4.80E1 9.00E2 1.20E3 4.72E0 2.99E1 9.00E2 1.20E3 1.05E0 1.14E19.00E2 7.53E2 2.60E−1 4.55E0 7.92E2 2.51E2 0.6~<2   7.39E−3 1.31E−2 / // / 1.57E1 4.80E1 9.00E2 1.20E3 3.49E0 2.75E1 9.00E2 1.20E3 8.65E−11.14E1 9.00E2 7.53E2 2~<6 2.46E−2 4.36E−2 / / / / / / / / 1.05E1 4.80E19.00E2 1.20E3 / / / / the rigor grade T_(Hemin) = 200 d segments of themeasured leak rate criterion for gross-leak R_(Ar0max) (Pa · cm³/s)cavity volume 7.95E−4 2.39E−3 7.95E−3 2.39E−2 V R_(2max) L_(max)t_(3min) t_(3max) t_(4max) t_(5max) t_(3min) t_(3max) t_(4max) t_(5max)t_(3min) t_(3max) t_(4max) t_(5max) t_(3min) t_(3max) t_(4max) t_(5max)cm³ Pa · cm³/s Pa · cm³/s h h s s h h s s h h s s h h s s 0.002~<0.0062.46E−6 4.36E−6  1.83E−1 2.09E0 2.38E2 7.53E1 / / / / / / / / / / / /0.006~<0.02  7.39E−6 1.31E−5  6.10E−1 5.60E0 7.14E2 2.26E2  1.57E−12.09E0 2.37E2 7.53E1 / / / / / / / / 0.02~<0.06 2.46E−5 4.36E−5 1.83E01.62E1 9.00E2 7.53E2  4.72E−1 6.15E0 7.92E2 2.51E2  1.05E−1 2.09E02.38E2 7.53E1 / / / / 0.06~<0.2  7.39E−5 1.31E−4 6.10E0 4.16E1 9.00E21.20E3 1.57E0 1.62E1 9.00E2 7.53E2  3.49E−1 5.60E0 7.14E0 2.26E2 8.65E−2 2.09E0 2.37E2 7.53E1 0.2~<0.6 2.46E−4 4.36E−4 1.83E1 1.14E19.00E2 1.20E3 4.72E0 4.55E1 9.00E2 1.20E3 1.05E0 1.62E1 9.00E2 7.53E2 2.60E−1 6.15E0 7.92E2 2.51E2 0.6~<2   7.39E−4 1.31E−3 6.10E1 2.75E29.00E2 1.20E3 1.57E1 1.14E2 9.00E2 1.20E3 3.49E0 4.16E1 9.00E2 1.20E3 8.65E−1 1.62E1 9.00E2 7.53E2 2~<6 2.46E−3 4.36E−3 1.83E2 4.80E2 9.00E21.20E3 4.72E1 2.99E2 9.00E2 1.20E3 1.05E1 1.14E1 9.00E2 1.20E3 2.60E04.55E1 9.00E2 1.20E3  6~<20 7.39E−3 1.31E−2 / / / / 1.57E2 4.80E2 9.00E21.20E3 3.49E1 2.75E2 9.00E2 1.20E3 8.65E0 1.14E2 9.00E2 1.20E3 20~<602.46E−2 4.36E−2 / / / / / / / / 1.05E2 4.80E2 9.00E2 1.20E3 2.60E12.99E2 9.00E2 1.20E3  60~<200 7.39E−2 1.31E−1 / / / / / / / / / / / /8.65E1 4.80E2 9.00E2 1.20E3 the rigor grade T_(Hemin) = 2000 d segmentsof the measured leak rate criterion for gross-leak R_(Ar0max) (Pa ·cm³/s) cavity volume 7.95E−4 2.39E−3 7.95E−3 2.39E−2 V R_(2max) L_(max)t_(3min) t_(3max) t_(4max) t_(5max) t_(3min) t_(3max) t_(4max) t_(5max)t_(3min) t_(3max) t_(4max) t_(5max) t_(3min) t_(3max) t_(4max) t_(5max)cm³ Pa · cm³/s Pa · cm³/s h h s s h h s s h h s s h h s s 0.0006~<0.002 7.39E−8 1.31E−7 / 1.27E1 7.14E1 6.68E2 / / / / / / / / / / / /0.002~<0.006 2.46E−7 4.36E−7 / 1.27E1 2.38E2 1.20E3 / 1.27E1 7.92E17.15E2 / / / / / / / / 0.006~<0.02  7.39E−7 1.31E−6 / 1.27E1 7.14E21.20E3 / 1.27E1 2.37E2 1.20E3 / 1.27E1 7.14E1 6.68E2 / / / / 0.02~<0.062.46E−6 4.36E−6 1.83E0 2.09E1 9.00E2 7.53E2 / 1.27E1 7.92E2 1.20E3 /1.27E1 2.38E2 1.20E3 / 1.27E1 7.92E1 7.15E2 0.06~<0.2  7.39E−6 1.31E−56.10E0 5.60E1 9.00E2 1.20E3 1.57E0 2.09E1 9.00E2 7.53E2 / 1.27E1 7.14E21.20E3 / 1.27E1 2.37E2 1.20E3 0.2~<0.6 2.46E−5 4.36E−5 1.83E1 1.62E29.00E2 1.20E3 4.72E0 6.15E1 9.00E2 1.20E3 1.05E0 2.09E1 9.00E2 7.53E2 /1.27E1 7.92E2 1.20E3 0.6~<2   7.39E−5 1.31E−4 6.10E1 4.16E2 9.00E21.20E3 1.57E1 1.62E2 9.00E2 1.20E3 3.49E0 5.60E1 9.00E2 1.20E3  8.65E−12.09E1 9.00E2 7.53E2 2~<6 2.46E−4 4.36E−4 1.83E2 1.14E3 9.00E2 1.20E34.72E1 4.55E2 9.00E2 1.20E3 1.05E1 1.62E1 9.00E2 1.20E3 2.60E0 6.15E19.00E2 1.20E3  6~<20 7.39E−4 1.31E−3 / / / / 1.57E2 1.14E3 9.00E2 1.20E33.49E1 4.16E2 9.00E2 1.20E3 8.65E0 1.62E2 9.00E2 1.20E3 20~<60 2.46E−34.36E−3 / / / / / / / / 1.05E2 1.14E3 9.00E2 1.20E3 2.60E1 4.55E2 9.00E21.20E3  60~<200 7.39E−3 1.31E−2 / / / / / / / / / / / / 8.65E1 1.14E39.00E2 1.20E3

TABLE 2 Fixed scheme of helium-argon pressuring method after argonprefilling for the cumulative helium mass spectrometric combination testthe rigor grade T_(Hemin) = 20 d segments of Condition of the measuredleak rate criterion for gross-leak R_(Ar0max) (Pa · cm³/s) cavity volumepressuring helium 7.95E−4 2.39E−3 7.95E−3 2.39E−2 V P_(E) t₁ R_(1max)L_(max) t_(2max) t_(4max) t_(5max) t_(2max) t_(4max) t_(5max) t_(2max)t_(4max) t_(5max) t_(2max) t_(4max) t_(5max) cm³ P₀ h Pa · cm³/s Pa ·cm³/s h s s h s s h s s h s s 0.002~<0.006 4 5 4.89E−6 4.36E−5 2.57E02.38E2 7.53E1 / / / / / / / / / 4 40 3.91E−5 2.14E0 0.006~<0.02  4 51.47E−5 1.31E−4 7.02E0 7.14E2 2.26E2 2.57E0 2.37E2 7.53E1 / / / / / / 440 1.17E−4 5.74E0 2.14E0 0.02~<0.06 4 5 4.89E−5 4.36E−4 2.08E1 9.00E27.53E2 7.73E0 7.92E2 2.51E2 2.57E0 2.38E2 7.53E1 / / / 4 20 1.95E−41.81E1 6.78E0 2.28E0 0.06~<0.2  4 5 1.47E−4 1.31E−3 4.80E1 9.00E2 1.20E32.08E1 9.00E2 7.53E2 7.02E0 7.14E2 2.26E2 2.57E0 2.37E2 7.53E1 4 102.93E−4 1.95E1 6.59E0 2.42E0 0.2~<0.6 4 5 4.89E−4 4.36E−3 4.80E1 9.00E21.20E3 4.80E1 9.00E2 1.20E3 2.08E1 9.00E2 7.53E2 7.73E0 7.92E2 2.51E2 210 4.89E−4 1.95E1 7.25E0 0.6~<2   4 5 1.47E−3 1.31E−2 4.80E1 9.00E21.20E3 4.80E1 9.00E2 1.20E3 4.80E1 9.00E2 1.20E3 2.08E1 9.00E2 7.53E2 210 1.47E−3 1.95E1 2~<6 4 5 4.89E−3 4.36E−2 4.80E1 9.00E2 1.20E3 4.80E19.00E2 1.20E3 4.80E1 9.00E2 1.20E3 4.80E1 9.00E2 1.20E3 2 10 4.89E−3 6~<20 4 2.5 7.33E−3 1.31E−1 / / / 4.80E1 9.00E2 1.20E3 4.80E1 9.00E21.20E3 4.80E1 9.00E2 1.20E3 2 5 7.33E−3 20~<60 4 2.5 2.44E−2 4.36E−1 / // / / / 4.80E1 9.00E2 1.20E3 4.80E1 9.00E2 1.20E3 2 5 2.44E−2 the rigorgrade T_(Hemin) = 200 d segments of Condition of the measured leak ratecriterion for gross-leak R_(Ar0max) (Pa · cm³/s) cavity volumepressuring helium 7.95E−4 2.39E−3 7.95E−3 2.39E−2 V P_(E) t₁ R_(1max)L_(max) t_(2max) t_(4max) t_(5max) t_(2max) t_(4max) t_(5max) t_(2max)t_(4max) t_(5max) t_(2max) t_(4max) t_(5max) cm³ P₀ h Pa · cm³/s Pa ·cm³/s h s s h s s h s s h s s 0.0006~<0.002  4 10 2.93E−8 1.31E−6 4.10E17.14E1 8.77E2 / / / / / / / / / 4 40 1.17E−7 1.03E1 5.64E2 0.002~<0.0064 5 4.89E−8 4.36E−6 7.87E1 2.38E2 1.20E3 7.87E1 7.92E1 1.12E3 / / / / // 4 40 3.91E−7 1.03E1 9.72E2 1.03E1 5.98E2 0.006~<0.02  4 5 1.47E−71.31E−5 7.87E1 7.14E2 1.20E3 7.87E1 2.37E2 1.20E3 7.87E1 7.14E1 1.03E2 // / 4 40 1.17E−6 1.03E1 4.38E2 1.03E1 9.71E2 1.03E1 5.64E2 0.02~<0.06 45 4.89E−7 4.36E−5 7.87E1 9.00E2 1.20E3 7.87E1 7.92E2 1.20E3 7.87E12.38E2 1.20E3 7.87E1 7.92E1 1.12E2 4 20 1.95E−6 2.76E1 7.53E2 2.05E12.05E1 2.05E1 7.73E2 0.06~<0.2  4 5 1.47E−6 1.31E−4 8.09E1 9.00E2 1.20E37.87E1 9.00E2 1.20E3 7.87E1 7.14E2 1.20E3 7.87E1 2.37E2 1.20E3 4 25.86E−6 7.57E1 2.76E1 7.53E2 2 05E1 2.05E1 0.2~<0.6 4 5 4.89E−6 4.36E−42.25E2 9.00E2 1.20E3 8.87E1 9.00E2 1.20E3 7.87E1 9.00E2 1.20E3 7.87E17.92E2 1.20E3 2 10 4.89E−6 2.23E2 8.66E1 7.67E1 7.67E1 4 20 1.95E−52.19E2 8.33E1 2.76E1 7.53E2 2.05E1 9.00E2 1.20E3 2 40 1.95E−5 2.11E27.88E1 2.61E1 1.95E1 0.6~<2   4 5 1.47E−5 1.31E−3 4.80E2 9.00E2 1.20E32.25E2 9.00E2 1.20E3 8.09E1 9.00E2 1.20E3 7.87E1 9.00E2 7.53E2 2 101.47E−5 2.23E2 7.88E1 7.67E1 4 10 2.93E−5 2.23E2 7.89E1 4.10E1 2 202.93E−5 2.19E2 7.57E1 3.90E1 2~<6 4 5 4.89E−5 4.36E−3 4.80E2 9.00E21.20E3 4.80E2 9.00E2 1.20E3 2.25E2 9.00E2 1.20E3 8.87E1 9.00E2 1.20E3 210 4.89E−5 2.23E2 8.66E1  6~<20 4 2.5 7.33E−5 1.31E−2 / / / 4.80E29.00E2 1.20E3 4.80E2 9.00E2 1.20E3 4.80E2 9.00E2 1.20E3 2 5 7.33E−520~<60 4 2.5 2.44E−4 4.36E−2 / / / / / / 4.80E2 9.00E2 1.20E3 4.80E29.00E2 1.20E3 2 5 2.44E−4  60~<200 4 2.5 7.33E−4 1.31E−1 / / / / / / / // 4.80E2 9.00E2 1.20E3 2 5 7.33E−4 the rigor grade T_(Hemin) = 2000 dsegments of Condition of the measured leak rate criterion for gross-leakR_(Ar0max) (Pa · cm³/s) cavity volume pressuring helium 7.95E−4 2.39E−37.95E−3 2.39E−2 V P_(E) t₁ R_(1max) L_(max) t_(2max) t_(4max) t_(5max)t_(2max) t_(4max) t_(5max) t_(2max) t_(4max) t_(5max) t_(2max) t_(4max)t_(5max) cm³ P₀ h Pa · cm³/s Pa · cm³/s h s s h s s h s s h s s0.002~<0.006 5 180 2.19E−8 4.36E−7 1.85E2 2.38E2 1.20E3 1.85E2 7.92E11.20E3 / / / / / / 0.006~<0.02  5 60 2.19E−8 1.31E−6 5.46E2 7.14E21.20E3 5.46E2 2.37E2 1.20E3 5.46E2 7.14E1 1.20E3 / / / 0.02~<0.06 5 202.43E−8 4.36E−6 1.44E3 9.00E2 1.20E3 1.44E3 7.92E2 1.20E3 1.44E3 2.38E21.20E3 1.44E3 7.92E1 1.20E3 4 40 3.91E−8 9.60E2 9.60E2 9.60E2 9.60E20.06~<0.2  4 10 2.93E−8 1.31E−5 3.08E3 9.00E2 1.20E3 3.08E3 9.00E21.20E3 3.08E3 7.14E2 1.20E3 3.08E3 2.37E2 1.20E3 4 40 1.17E−7 9.60E29.60E2 9.60E2 9.60E2 0.2~<0.6 4 5 4.89E−8 4.36E−5 4.80E3 9.00E2 1.20E34.80E3 9.00E2 1.20E3 4.80E3 9.00E2 1.20E3 4.80E3 7.92E2 1.20E3 2 104.89E−8 4.80E3 4.80E3 4.80E3 4.80E3 4 20 1.95E−7 1.74E3 1.74E3 1.74E31.74E3 2 40 1.95E−7 1.73E3 1.73E3 1.73E3 1.73E3 0.6~<2   4 5 1.47E−71.31E−4 4.80E3 9.00E2 1.20E3 4.80E3 9.00E2 1.20E3 4.80E3 9.00E2 1.20E34.80E3 9.00E2 1.20E3 2 10 1.47E−7 4.80E3 4.80E3 4.80E3 4.80E3 4 205.86E−7 1.74E3 1.74E3 1.74E3 1.74E3 2 40 5.86E−7 1.73E3 1.73E3 1.73E31.73E3 2~<6 4 5 4.89E−7 4.36E−4 4.80E3 9.00E2 1.20E3 4.80E3 9.00E21.20E3 4.80E3 9.00E2 1.20E3 4.80E3 9.00E2 1.20E3 2 10 4.89E−7 4.80E34.80E3 4.80E3 4.80E3 4 20 9.77E−7 3.08E3 3.08E3 3.08E3 3.08E3 2 409.77E−7 3.08E3 3.08E3 3.08E3 3.08E3  6~<20 4 2.5 7.33E−7 1.31E−3 / / /4.80E3 9.00E2 1.20E3 4.80E3 9.00E2 1.20E3 4.80E3 9.00E2 1.20E3 4 102.93E−6 3.08E2 3.08E2 3.08E2 2 20 2.93E−6 3.08E2 3.08E2 3.08E2 20~<60 42.5 2.44E−6 4.36E−3 / / / / / / 4.80E3 9.00E2 1.20E3 4.80E3 9.00E21.20E3 4 10 9.77E−6 3.08E2 3.08E2 2 20 9.77E−6 3.08E2 3.08E2  60~<200 42.5 7.33E−6 1.31E−2 / / / / / / / / / 4.80E3 9.00E2 1.20E3 4 10 2.93E−53.08E2 2 20 2.93E−5 3.08E2Step S4 of Removing the Absorbed Helium-Argon and Keeping InternalP_(Ar0) and P_(He0):

before a combination test, the absorbed helium gas formed on the surfaceof the component under test during helium-argon prefilling, argonprefilling or helium-argon pressuring should be removed; the absorbedargon gas formed on the surface of the component under test should beremoved if the component has been in wet environment; The removal of theabsorption should be carried out in a dry environment having normalpartial pressure of argon gas and helium gas in air. The removal may beaccelerated by blow of dry air but not by heated baking or vacuum.

Any direct or potential damage should not be occurred on the componentunder test during the removing process; and the time used for theremoving process should not exceed generally no longer than (⅔) of themaximum detection-waiting time of fine-leak test t_(max) to guaranteethat the combination test of the component under test is completedwithin the maximum detection-waiting time.

After removing the absorbed helium and argon, the surface absorbedhelium of the component under test and the measured leak rate formed byabsorbed helium should be verified. The absorbed argon leak rate R_(Ara)of gross-leak test should be no more than ⅓ of the criterion for argonmeasured leak rate R_(Ar0max). The leak rate of absorbed helium R_(a) offine-leak test should be no more than ⅓ of the criterion for heliummeasured leak rate R_(max). Such verification may be carried out with 3comparison samples with the same shape and appearance, which have beenverified to be sealed components without any leak; the absorption leakrate may be obtained by subtracting the stable background value of theleak detector from the actual tested leak rate.

After helium-argon prefilling, argon prefilling or heliumpressuring-argon of a component under test, its internal partialpressure of argon gas should be maintained the same value P_(Ar0), andthe helium partial pressure no less than P_(He0). When placed in vacuum(including vacuum test) or in gas lacking the normal partial pressure ofargon or helium in the air for a time of a that no more than ⅙t_(max),the component under test is placed in the normal air for a period noless than 3.23a to keep the internal argon partial pressure no less than0.9P_(Ar0) and the internal helium partial pressure no less than0.9P_(He0); and then the argon measured leak rate criterion ofgross-leak test should be taken the value as 0.9R_(Ar0max), and thehelium measured leak rate criterion of fine-leak test as still R_(max).

Step S5 of Calibrating:

the calibrations for the Cumulative Helium Leak Detector of the presentinvention should be carried out respectively for the argon gas leak rateof gross-leak test and for the helium gas leak rate of fine-leak testand able to effectively cover the ranges of criterions for gross-leaktest and fine-leak test. During calibration, the standard leak apertureshould be placed in a test chamber or connect to a test chamber, orlinked with a test chamber in the shortest distance. The calibrationshould be carried out at each time when the system is stable afterstarting the detector or changing the device state (such as changing atest chamber, regenerating the cryogenic pump, and adjusting the valve).

Step S6 of Comparing the Maximum and Minimum Detection-Waiting Time ofFine-Leak Test:

for helium-argon prefilling method, the fine-leak detection-waiting timet₃, which is from the ending of sealing to the beginning of thecombination test, should be no more than the t_(3max) in step S2.4 ofdesigning; when the measured leak rate criterion of fine-leak testR_(2max) is no less than 0.905R_(0max), t₃ should be no less than theminimum detection-waiting time t_(3min) in step S2.5 of designing. Forhelium-argon pressuring method after argon prefilling, helium-argonpressuring method after helium-argon prefilling and helium-argonmulti-pressuring method after argon prefilling, the detection-waitingtime of fine-leak t₂, t_(3n) or t_(2n), which is from the ending of thelast helium-argon pressuring to the beginning of the combination test,should be no more than the maximum detection-waiting time t_(2max),t_(3max), or t_(2n.max) in step S2.4 of designing.

When the detection-waiting time t₃ is less than t_(3min), the testshould be done after the condition satisfying the requirements. When thedetection-waiting time does not exceed the maximum detection-waitingtime, the test procedure enters step S7; when the detection-waiting timeis longer than the maximum detection-waiting time, test is carried outagain starting from step S2 of designing, step S3 of helium-argonpressuring, and step S4 of removing absorbed helium-argon.

Step S7 of Gross-Leak Test:

in order to prevent misjudge or detection missing, the gross-leakdetection time t₄, which is from putting the component under test in thechamber, flushing the detecting chamber, and vacuuming to the beginningof reading the argon measured leak rate of gross-leak test R_(Ar),should be no less than the minimum gross-leak detection time t_(4min)and no more than the time t_(4max) designing in step S2.5. The timet_(4min) is the maximum time that the argon background leak rate R_(Arb)falling to the value of (⅓) R_(Ar0max) when the system is stable and nocomponent under test is placed in the detecting chamber.

For gross-leak test, the argon measured leak rate can be obtained bycumulating the leakage of argon or not, but the leakage gas channelshould not connected to the cryogenic pump.

If the measured leak rate R_(Ar) is no less than the criterionR_(Ar0max), the component under test is judged as failed for gross-leaktest; if R_(Ar)<R_(Ar0max), the gross-leak test is judged as acceptable,and the component is still placed in the vacuumed detecting chamber andis proceeded with Step S8 of fine-leak test. Once the gross-leakhappens, the gross-leak test should be preceded again with empty chamberto make sure the adsorbed argon leak rate R_(Arb) less than ⅓R_(Ar0max)at the time of t_(4min).

The rules of keeping P_(Ar0), P_(He0) and the gross-leak rate criterionin step S4 should be done still when the detection-waiting time does notexceed the maximum detection-waiting time t_(max); the next gross-leaktest may be more possible for detection missing, if the component undertest placed in the air for less than 3.23 times of the last detectiontime a between two combination test after sealing or once helium-argonpressuring, or the measured gross-leak test criterion was not0.9R_(Ar0max).

Step S8 of Fine-Leak Test:

according to the property of the cumulative helium mass spectrometriccombination leak detector which is employed, when the criterion formeasured leak rate for fine-leak is less than a certain value (such as5×10⁻⁴ Pa·cm³/s or 1×10⁻⁵ Pa·cm³/s), the test gas passes through thecryogenic pump and has a cumulative test; when the criterion formeasured leak rate for fine-leak is more than a certain value (such as5×10⁻⁴ Pa·cm³/s or 1×10⁻⁴ Pa·cm³/s), test gas can either pass though thecryogenic pump or not and can either have a cumulative test or not.

In order to prevent misjudge or detection missing, the fine-leakdetection time t₅, which is from putting the component under test in thechamber, to flushing the detecting chamber, vacuuming, cumulating heliumand reading the number, should be no less than the minimum fine-leakdetection time t_(5min) and no more than the time t_(5max) designing instep S2.5. the time t_(5min) is the maximum time that the heliumbackground leak rate R_(b) falling to the value of (⅓) R_(max) (such asR_(1max), R_(2max), R_(2n.max), or R_(1n.max)) when the system is stableand no component under test is placed in the detecting chamber.

If the helium measured leak rate R (such as R₁, R₂, R_(2n), or R_(1n))is greater than the criterion R_(max), the component under test isjudged as failed for fine-leak test; if R≤R_(max), the fine-leak test isjudged as acceptable, and S9 is proceeded.

When the gross-leak components under test can be effectively refused anddone the rules of keeping P_(He0) and criterion in step S4, within themaximum detection-waiting time of fine-leak test, the sequential ormultiple fine-leak tests of a component under test are efficient afterhelium-argon prefilling, or helium-argon pressuring.

Step S9 of Complementally Testing the Bigger Gross-Leak:

to prevent gross-leak detection missing, an effective method such asappearance detecting method is added to detect the bigger gross-leakwhich may be undetected in step S7 for the component under test whichhas passed step S7 of gross-leak test and step S8 of fine-leak test,especially with the time t_(4max) designed in step S2.6 less than 900 s.If bigger gross-leak is found to exist in complemented test, thehermeticity of the component under test is judged as failed; else thehermeticity of the component under test is judged as acceptable.

If no effective method is taken for complemented test of biggergross-leak, the hermeticity of the component under test can also befinally judged as acceptable via S7 and S8, but there exists a certainrisk of false test for gross-leak at this time.

Step S10 of Quantitative Detection:

if quantitative detection on τ_(He) or L of a component under test isneeded, in step S1, the detailed test method, the flexible scheme,higher rigor grade τ_(Hemin) and available lower criterion R_(Ar0max)are required. For the first detection, helium-argon prefilling method orhelium-argon pressuring method after argon prefilling is selected; forthe repetitive tests, helium-argon pressuring method after helium-argonprefilling or helium-argon multi-pressuring method after argonprefilling is selected.

In the designing of step S2.6, the flexible scheme should be design fora certain cavity volume V, which is including the ratio value ofhelium-argon prefilling method k=0.21, each helium-argon pressuring timet_(1i)<0.1τ_(Hemin), the maximum detection-waiting time t_(max)(t_(3max), t_(2max), t_(3n.max), or t_(2n.max))<0.1τ_(Hemin), the heliummeasured leak rate criterion of fine-leak test R_(max) (R_(2max),R_(1max), R_(2n.max), or R_(1n.max)), relative P_(E) (or P_(En)),t_(4max), t_(5max), t_(3min), etc.

In step S8 of fine-leak test, the absorbed helium leak rateR_(a)<0.1R_(max) should be verified by using the same shape sampleswhich has passed the fine-leak test; Then the helium leak ratebackground R_(b) when the detecting chamber is load-free is read, andthe measured leak rate R (R₂, R₁, R_(2n), or R_(1n)) of fine-leak testof a component under test is read.

For the component under test with acceptable hermeticity τ_(Hemin), theactual helium measured leak rate R′ (R₂′, R₁′, R_(2n)′, or R_(1n)′) of acomponent under test is obtained by formula (36),R′=R−R _(b)  (36)

where R′ comprises the leak rate of absorbed helium of a component undertest R_(a) and each test deviation.

for the accepted component in hermeticity test by using helium-argonprefilling method, the helium gas exchange constant τ_(He) can beapproximately obtained by formula (37) through asymptotic fittingmethod,

$\begin{matrix}{R_{2}^{\prime} = {\frac{V}{\tau_{He}}\left\lbrack {{{kP}_{0}{\exp\left( {- \frac{t_{3}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\rbrack}} & (37)\end{matrix}$

in the condition of

${t_{3} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}\mspace{14mu}{and}\mspace{14mu}{kP}_{0}} \geqslant {10\; P_{{He}\; 0}}},$the helium gas exchange constant τ_(He) can be approximately obtained byformula (38),

$\begin{matrix}{\tau_{He} = {\tau_{{He}\mspace{11mu}\min}\frac{R_{2\;\max}}{R_{2}^{\prime}}}} & (38)\end{matrix}$

for the accepted component in hermeticity test by using helium-argonpressuring method after argon prefilling, the helium gas exchangeconstant τ_(He) can be approximately obtained by formula (39) throughasymptotic fitting method,

$\begin{matrix}{R_{1}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{{P_{E}\left\lbrack {1 - {\exp\left( {- \frac{t_{1}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\}}} & (39)\end{matrix}$

or it can be obtained by formula (40) in the condition oft₁≤0.1τ_(Hemin), t₂≤0.1τ_(Hemin), P_(E)t₁/τ_(He)≥10P_(He0),

$\begin{matrix}{\tau_{He} = {\tau_{{He}\mspace{11mu}\min}\sqrt{\frac{R_{1\;\max}}{R_{1}^{\prime}}}}} & (40)\end{matrix}$

for the accepted component in hermeticity test by using helium-argonpressuring method after helium-argon prefilling, τ_(He) can beapproximately obtained by formula (41) through asymptotic fittingmethod,

$\begin{matrix}{R_{2\; n}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0\; n}}{\tau_{He}}} \right)}} + {\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.i\; n}}{\tau_{He}}} \right)}}}} \right\}{\exp\left( {- \frac{t_{2n}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\}}} & (41)\end{matrix}$

for the accepted component in hermeticity test by using helium-argonmulti-pressuring method, τ_(He) can be approximately obtained by formula(42) through asymptotic fitting method,

$\begin{matrix}{R_{1\; n}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.i\; n}}{\tau_{He}}} \right)}{\exp\left( {- \frac{t_{2n}}{\tau_{He}}} \right)}}} + P_{{He}\; 0}} \right\}}} & (42)\end{matrix}$

then the equivalent standard leak rate L can be obtained by formula (43)when τ_(He) has been gotten.

$\begin{matrix}{L = {\frac{{VP}_{0}}{\tau_{He}}\sqrt{\frac{M_{He}}{M_{A}}}}} & (43)\end{matrix}$

Both of τ_(He) and L can be the quantitative detection results withcertain detection deviation

In this invention of the combination test by using argon as gross-leaktracer gas and using helium as fine-leak tracer gas, the helium-argonpressuring method after argon prefilling and helium-argonmulti-pressuring method after argon prefilling is added in optionalspecific method; and the range of 2.39×10⁻² Pa·cm³/s is added in argonmeasured leak rate criterion R_(Ar0max) for gross-leak test.Furthermore, a series of methods is provided to reduce and prevent thedetection missing and misjudge in fine-leak/gross-leak test, includingfurther quantitative expansion of the maximum detection-waiting time,the improved removal method of absorbed helium-argon, the method to keepthe internal partial pressure of helium-argon and to rule correspondingcriterion. Besides, this invention provides the methods toquantitatively determine the minimum pressure during pressing helium,the minimum detection-waiting time of helium-argon prefilling method,the maximum and minimum gross-leak detection time, and the maximum andminimum fine-leak detection time. Thereby, the available rigor gradeτ_(Hemin) and the cavity volume V are expanded, and this inventioneffectively prevents the detection missing and misjudge ingross/fine-leak test. Not only the invention makes the test moreapplicable and convenient, but also solves the feasibility andcredibility problems of the leak test.

Preferred Embodiment 2

The preferred embodiment provides a combination testing method by usingargon as gross-leak test tracer gas and using helium as fine-leak testtracer gas. The method comprises at least step S1 of selecting:helium-argon prefilling method is the specific method for the firsttest, and helium-argon pressuring method after helium-argon prefillingis the specific method for repetitive hermeticity test; or helium-argonpressuring method after argon prefilling is the specific method for thefirst test, and helium-argon multi-pressuring method after argonprefilling is the specific method for repetitive hermeticity tests. Thecriterion for gross-leak test is taken as argon measured leak rateR_(Ar0max), and the basic criterion for fine-leak test is taken as rigorgrade τ_(Hemin) and the characterized criterion as helium measured leakrate R_(max). For the first hermeticity test, the fixed scheme or theflexible scheme can be selected, and the flexible scheme should beselected for repetitive tests. For fixed scheme, the rigor gradeτ_(Hemin) can be taken the value as 2000 days, 200 days, 20 days orother values, and the criterion R_(Ar0max) is selected as the value of7.95×10⁻⁴ Pa·cm³/s, 2.39×10⁻³ Pa·cm³/s, 7.95×10⁻³ Pa·cm³/s, 2.39×10⁻²Pa·cm³/s or other values. The rigor grade and the criterion for flexiblescheme can be taken the same value as the fixed scheme, or other values.

The subsequent steps of the method can be the steps as shown inpreferred embodiment 1, or other subsequent steps that can expand theapplicable rigor grade and range of cavity volume for the combinationtest method above mentioned, and can improve the feasibility andcredibility of the test.

As known by those skilled in the art, the present invention which hasbeen described with reference to the embodiments can make variouschanges and equivalent replacements on these characteristics andembodiments without departing from the spirit and scope of the presentinvention. Additionally, under the guidance of the present invention,these characteristics and embodiments can be modified to be adapted forspecific conditions without departing from the spirit and scope of thepresent invention. For example, the methods, including the method offurther quantitatively expanding the maximum detection-waiting time, theway to keep the internal helium/argon partial pressure of the componentunder test, the method of determining the maximum and minimum detectiontime, the method of designing the minimum detection-waiting time, therule of helium pressuring pressure no less than 2 times of P₀, themethod of quantitative detection, can be exchanged directly or byconverting certain conditions to apply for the improvement of a heliummass spectrometric fine-leak test method based on quantitativelydetermined the maximum detection-waiting time, a helium massspectrometric fine-leak test method for helium pressuring after heliumprefilling or multi-helium pressuring, or a cumulative helium massspectrometric gross/fine-leak combination test method for thehermeticity test; the method of designing helium measured leak ratecriterion for repetitive tests is available for improving the heliummass spectrometric fine-leak test method in the condition ofmulti-helium pressuring or helium pressuring after helium prefilling;the method of determining the maximum and minimum gross-leak detectiontime through equaling R_(Ar0max) to R_(0max) can be used to improve acumulative helium mass spectrometric gross/fine-leak combination testmethod for the hermeticity test. Accordingly, the present invention isnot limited to the specific embodiments disclosed herein and allembodiments which fall within the claims of the present invention belongto the scope protected by the present invention.

What is claimed is:
 1. A combination test method by using argon asgross-leak tracer gas and using helium as fine-leak tracer gas,comprising a step S1 of selecting: a helium-argon prefilling method isselected for a first hermeticity test and a helium-argon pressuringmethod after helium-argon prefilling is selected for repetitivehermeticity test, or a helium-argon pressuring method after argonprefilling is selected for the first hermeticity test and a helium-argonmulti-pressuring method after argon prefilling is selected for therepetitive hermeticity test; wherein a detectable range of cavity volumeV, detected by a fixed scheme of the helium-argon prefilling method, ofa component under detection is from 0.0006 cm³ to less than 200 cm³ whena rigor grade τ_(Hemin) of the first hermeticity test is 2000 days; adetectable range of cavity volume V, detected by a fixed scheme of thehelium-argon pressuring method after helium-argon prefilling, of thecomponent under detection is from 0.002 cm³ to less than 200 cm³ whenthe rigor grade τ_(Hemin) of the first hermeticity test is 2000 days; adetectable range of cavity volume V, detected by a fixed scheme of thehelium-argon prefilling method, of the component under detection is from0.002 cm³ to less than 6 cm³ when the rigor grade τ_(Hemin) of the firsthermeticity test is 20 days; a detectable range of cavity volume V,detected by a fixed scheme of the helium-argon pressuring method afterhelium-argon prefilling, of the component under detection is from 0.002cm³ to less than 60 cm³ when the rigor grade τ_(Hemin) of the firsthermeticity test is 20 days; the first hermeticity test comprises onegross-leak test and one fine-leak test, the repetitive hermeticity testalso comprises one gross-leak test and one fine-leak test; a argonmeasured leak rate criterion R_(Ar0max) is taken as a criterion for thegross-leak test, and for fine-leak test, the rigor grade τ_(Hemin) istaken as a basic criterion and a helium measured leak rate criterionR_(max) of the fine-leak test is taken as a characteristic criterion;and either a fixed scheme or a flexible scheme is taken for the firsthermeticity test, and the flexible scheme is taken for the repetitivehermeticity test; wherein the fixed scheme is a scheme of according tothe selected rigor grade τ_(Hemin), selected method and selected argonmeasured leak rate criterion R_(Ar0max) of the gross-leak test, settingthe cavity volume segments of component under detection, the fixedcondition of helium-argon prefilling or helium-argon pressuring afterargon prefilling, the helium measured leak rate criterion R_(max) of thefine-leak test, a maximum and minimum detection-waiting time of thefine-leak test, a maximum gross-leak detection time, and a maximumfine-leak detection time; wherein the flexible scheme is a scheme ofaccording to the selected rigor grade τ_(Hemin), selected method,selected argon measured leak rate criterion R_(Ar0max) of the gross-leaktest, and the cavity volume of the component under detection, setting afixed ratio of argon gas of the helium-argon prefilling method, thehelium-argon prefilling method, or the helium-argon pressuring method, aflexible ratio of helium gas of the helium-argon prefilling method orthe helium-argon pressuring method, a flexible value of helium measuredleak rate criterion R_(max) of the fine-leak test, the maximum andminimum detection-waiting time of the fine-leak test, the maximumgross-leak detection time, and the maximum fine-leak detection time;wherein the rigor grade τ_(Hemin) of the fixed scheme is chosen as 2000days, 200 days, or 20 days according to a specification or a contract ofthe component under detection, and on a precondition that R_(Ar0max) islarger than 3 times of a surface absorbed argon leak rate R_(Ara) of thecomponent under detection stored in dry air, the argon measured leakrate criterion R_(Ar0max) of the gross-leak test is chosen as 7.95×10⁻⁴Pa·cm³/s, 2.39×10⁻³ Pa·cm³/s, 7.95×10⁻³ Pa·cm³/s or 2.39×10⁻² Pa·cm³/s,the rigor grade τ_(Hemin) is a constant of allowable minimum helium gasexchange time for an acceptable component under detection; the rigorgrade τ_(Hemin) of the flexible scheme is same as the fixed scheme or aflexible value, and the argon measured leak rate criterion R_(Ar0max) issame as the fixed scheme or a flexible value; a step S2 of designing:according to the selected method, scheme, τ_(Hemin) and R_(Ar0max),pressure and time conditions of helium-argon prefilling, argonprefilling, or helium-argon pressuring are designed; the helium measuredleak rate criterion R_(max) of the fine-leak test and the maximumdetection-waiting time t_(max) are designed; the maximum gross-leakdetection time t_(4max), the maximum fine-leak detection time t_(5max),and the minimum detection-waiting time t_(3min) of helium-argonprefilling method are designed; and the fixed scheme or the flexiblescheme is designed, wherein step S2.1, the pressure and time conditionsof helium-argon prefilling, argon prefilling or helium-argon pressuringare designed as follows: if the helium-argon prefilling method isselected for the first hermeticity test, the total gas pressure P is(1+10%)P₀ during the sealing of component under detection, with a firsthelium partial pressure P_(He) of (1+10%)kP₀, an argon partial pressureP_(Ar) of (1+10%) P_(Ar0), and the rest of the total gas is nitrogengas, wherein, P₀ is standard atmospheric pressure 1.013×10⁵ Pa; k is ahelium prefilling ratio P_(Hed)/P₀, wherein P_(Hed) is a helium partialpressure of a designed helium-argon prefilling when the total gaspressure is standard atmospheric pressure; P_(Ar0) is the normal partpressure of argon in atmosphere, P_(Ar0)=946 Pa; for the fixed scheme,k=0.21 is chosen; and k is a flexible value from 0.03 to 0.5 forflexible scheme; if helium-argon pressuring method after argonprefilling is selected for the first hermeticity test, the total gaspressure P is (1+10%)P₀ during the sealing of component under detection,with argon partial pressure (1+10%) P_(Ar0) and the rest of the totalgas is nitrogen gas; the bombed gas pressure is no more than 6P₀, inwhich there is an argon partial pressure P_(Ar) equal to P_(Ar0), and asecond helium partial pressure P_(E) is no less than 2P₀, helium-argonpressuring time t₁ is long enough to make sure that helium measured leakrate criterion R_(1max) reaches the detectable range of detectors; forthe repetitive hermeticity test, if the helium-argon pressuring methodafter helium-argon prefilling is selected, in the nth helium-argonpressuring, where the integer n is no less than 1, the argon partialpressure P_(Ar) is P_(Ar0), a third helium partial pressure P_(En) is noless than 2P₀ to prevent fine-leak detection missing; helium-argonpressuring time t_(1n) is obtained by formula 1, $\begin{matrix}\left. \begin{matrix}{t_{1\; n} \geqslant {\frac{1}{P_{En}}\left( {{\frac{1}{10e}{kP}_{0}t_{3.0\; n}} + {0.15{\sum\limits_{i = 1}^{n - 1}\;{P_{Ei}t_{1\; i}}}}} \right)}} \\{t_{1\; n} \geqslant {1.2\mspace{14mu} h}}\end{matrix} \right\} & {{formula}\mspace{14mu} 1}\end{matrix}$ wherein, t_(3.0n) is an interval time from the ending ofsealing of the component under detection to the ending of the nthhelium-argon pressuring; P_(Ei) and t_(1i) are the helium partialpressure and time in the ith helium-argon pressuring; and for therepetitive hermeticity test, if the helium-argon multi-pressuring methodafter argon prefilling is selected, in the nth helium-argon pressuring,where n is an integer no less than 2, the argon partial pressure P_(Ar)is P_(Ar0), the third helium partial pressure P_(En) is no less than 2P₀to prevent the fine-leak detection missing; helium-argon pressuring timet_(1n) is obtained by formula 1 when k=0; step S2.2, the helium measuredleak rate criterion R_(max) of fine-leak test is designed as follows:for the helium-argon prefilling method in the first hermeticity test,the component under detection is stored for a detection-waiting time t₃in normal atmosphere, helium measured leak rate criterion R_(2max) ofthe fine-leak test is obtained by formula 2, $\begin{matrix}{R_{2\;\max} = {\frac{{VkP}_{0}}{\tau_{{He}\mspace{11mu}\min}}{\exp\left( {- \frac{t_{3}}{\tau_{{He}\mspace{11mu}\min}}} \right)}}} & {{formula}\mspace{14mu} 2}\end{matrix}$ wherein, V denotes a cavity volume of the component underdetection; R_(2max) is obtained by approximate formula 3 in thecondition of${t_{3} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}},$$\begin{matrix}{R_{2\;\max} = \frac{{VkP}_{0}}{\tau_{{He}\mspace{11mu}\min}}} & {{formula}\mspace{14mu} 3}\end{matrix}$ for the helium-argon pressuring method after argonprefilling in the first hermeticity test, the component under detectionis stored in air after the sealing of the component under detection,bombed helium-argon for time t₁ and then stored for detection-waitingtime t₂, the helium measured leak rate criterion R_(2max) of thefine-leak test is obtained by formula 4, $\begin{matrix}{R_{1\;\max} = {{\frac{{VP}_{E}}{\tau_{{He}\mspace{11mu}\min}}\left\lbrack {1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{11mu}\min}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2}}{\tau_{{He}\mspace{11mu}\min}}} \right)}}} & {{formula}\mspace{14mu} 4}\end{matrix}$ or R_(1max) is obtained by approximate formula 5 in thecondition of${t_{1} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{2}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$$\begin{matrix}{R_{1\;\max} = \frac{{VP}_{E}t_{1}}{\tau_{{He}\mspace{11mu}\min}^{2}}} & {{formula}\mspace{14mu} 5}\end{matrix}$ for the helium-argon pressuring method after helium-argonprefilling in the repetitive hermeticity test, the helium measured leakrate criterion R_(2n.max) of fine-leak test after the nth, n is no lessthan 1, helium-argon pressuring is obtained by formula 6,$\begin{matrix}{R_{2{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} + {\sum\limits_{i = 1}^{n}{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}}} \right\}{\exp\left( {- \frac{t_{2n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} & {{formula}\mspace{14mu} 6}\end{matrix}$ wherein, t_(2.in) is the interval time from the ending ofthe ith helium-argon pressuring to the ending of nth pressuring;similarly, R_(2n.max) is obtained by approximate formula 7 in thecondition of${t_{1i} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu}\min}}},{t_{2n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$$\begin{matrix}{R_{2{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left\{ {{{kP}_{0}{\exp\left( {- \frac{t_{3.0n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} + {\frac{1}{\tau_{{He}\mspace{14mu}\min}}{\sum\limits_{i = 1}^{n}{P_{Ei}t_{1i}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}}}} \right\}}} & {{formula}\mspace{14mu} 7}\end{matrix}$ for the repetitive hermeticity test, in the condition of${t_{3.0n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{2n}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$R_(2n.max) is also obtained by approximate formula 8, $\begin{matrix}{R_{2{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left( {{kP}_{0} + {\frac{1}{\tau_{{He}\mspace{14mu}\min}}{\sum\limits_{i = 1}^{n}{P_{Ei}t_{1i}}}}} \right)}} & {{formula}\mspace{14mu} 8}\end{matrix}$ furthermore, when$\left( {\frac{1}{\tau_{{He}\mspace{14mu}\min}}{\sum\limits_{i = 1}^{n}{P_{Ei}t_{1i}}}} \right) \leqslant {\frac{1}{10}{kP}_{0}}$in the formula 8, R_(2n.max) is obtained by formula 9, $\begin{matrix}{R_{2{n.\max}} = \frac{{VkP}_{0}}{\tau_{{He}\mspace{14mu}\min}}} & {{formula}\mspace{14mu} 9}\end{matrix}$ for the helium-argon multi-pressuring method after argonprefilling in the repetitive hermeticity test, helium measured leak ratecriterion R_(1n.max) of fine-leak test after the nth helium-argonpressuring is obtained by formula 10, n is an integer no less than 2,$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}}\left\{ {\sum\limits_{i = 1}^{n}{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1i}}{\tau_{{He}\mspace{14mu}\min}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} \right\}{\exp\left( {- \frac{t_{2n}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} & {{formula}\mspace{14mu} 10}\end{matrix}$ or, R_(1n.max) is obtained by approximate formula 11 inthe condition of${t_{1i} \leqslant {\frac{1}{5}\tau_{{He}\mspace{14mu}\min}}},{t_{2n} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}},$$\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}^{2}}\left\lbrack {\sum\limits_{i = 1}^{n}{P_{Ei}t_{1i}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{{He}\mspace{14mu}\min}}} \right)}}} \right\rbrack}} & {{formula}\mspace{14mu} 11}\end{matrix}$ furthermore, when$t_{2.{in}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}\mspace{14mu}{and}\mspace{14mu} t_{1i}} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu}\min}}$in formula 11, R_(1n.max) is obtained by formula 12, $\begin{matrix}{R_{1{n.\max}} = {\frac{V}{\tau_{{He}\mspace{14mu}\min}^{2}}{\sum\limits_{i = 1}^{n}{P_{Ei}t_{1i}}}}} & {{formula}\mspace{14mu} 12}\end{matrix}$ step S2.3, the upper limit of the cavity volume isobtained by formula 13, $\begin{matrix}{V_{\max} = {\frac{L_{\max\; 0}\tau_{{He}\mspace{14mu}\min}}{P_{0}}\sqrt{\frac{M_{A}}{M_{He}}}}} & {{formula}\mspace{14mu} 13}\end{matrix}$ wherein, L_(max0) is the maximum detectable equivalentstandard leak rate, L_(max)=1.0 Pa·cm³/s; M_(He) is the molecular weightof helium in grams, M_(He)=4.003 g; M_(A) is the average molecularweight of air in grams, M_(A)=28.96 g; step S2.4, the maximumdetection-waiting time t_(max) of fine-leak test is designed:corresponding to the argon measured leak rate criterion R_(Ar0max) ofgross-leak rate test, R_(0max), which is the helium measured leak ratecriterion of gross-leak rate test when helium partial pressure equal toP_(He0) in the component under, is obtained by formula 14,$\begin{matrix}{R_{0\max} = {R_{{Ar}\; 0\;\max}\frac{P_{{He}\; 0}}{P_{{Ar}\; 0}}\sqrt{\frac{M_{Ar}}{M_{He}}}}} & {{formula}\mspace{14mu} 14}\end{matrix}$ wherein, P_(He0) is the helium partial pressure in normalatmosphere, P_(He0)=0.533 Pa; M_(Ar) is the molecular weight of argon ingrams, M_(Ar)=39.948 g; helium exchange time constant τ_(He0) ofgross-leak is obtained by formula 15, $\begin{matrix}{\tau_{{He}\; 0} = {{\frac{{VP}_{0}}{L_{0}}\sqrt{\frac{M_{He}}{M_{A}}}} = {\frac{{VP}_{{He}\; 0}}{R_{0\max}} = {\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\; 0\max}}\sqrt{\frac{M_{He}}{M_{Ar}}}}}}} & {{formula}\mspace{14mu} 15}\end{matrix}$ wherein, L₀ is the minimum detectable equivalent standardleak rate of gross-leak,${L_{0} = {R_{{Ar}\; 0\max}\frac{P_{0}}{P_{{Ar}\; 0}}\sqrt{\frac{M_{Ar}}{M_{A}}}}};$argon exchange time constant τ_(Ar0) of gross-leak is obtained byformula 16, $\begin{matrix}{\tau_{{Ar}\; 0} = {\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\; 0\max}} = {\tau_{{He}\; 0}\sqrt{\frac{M_{Ar}}{M_{He}}}}}} & {{formula}\mspace{14mu} 16}\end{matrix}$ helium exchange time constant τ_(He0.m) of medium-leak isobtained by formula 17, $\begin{matrix}{\tau_{{He}\; 0.m} = {\tau_{{He}\; 0}\frac{R_{0\max}}{R_{{ma}x}}}} & {{formula}\mspace{14mu} 17}\end{matrix}$ wherein, the helium measured leak rate criterion R_(max)of the fine-leak is less than R_(0max); for helium-argon prefillingmethod, when τ_(Hemin)>τ_(He0) and R_(2max)≥R_(0max), the maximumdetection-waiting time of the fine-leak test or combination testt_(3max) is obtained by formula 18, $\begin{matrix}{t_{3\max} = {{\frac{\tau_{{He}\mspace{14mu} m\; i\; n}\tau_{{He}\; 0}}{\tau_{{He}\mspace{14mu} m\; i\; n} - \tau_{{He}\; 0}}{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}}{\tau_{{He}\; 0}} \right)}} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}{VP}_{{He}\; 0}}{{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0\max}} - {VP}_{{He}\; 0}}{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0\max}}{{VP}_{{He}\; 0}} \right)}}}} & {{formula}\mspace{14mu} 18}\end{matrix}$ for the fixed scheme, t_(3max) is obtained by formula 19,$\begin{matrix}\left. \begin{matrix}{t_{3\max} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}{VP}_{{He}\; 0}}{{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0{{ma}x}}} - {VP}_{{He}\; 0}}{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0\max}}{{VP}_{{He}\; 0}} \right)}}} \\{t_{3\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}}}\end{matrix} \right\} & {{formula}\mspace{14mu} 19}\end{matrix}$ for the helium-argon prefilling method, whenτ_(Hemin)>τ_(He0) and R_(2max)<R_(0max), t_(3max) is obtained by formula20, $\begin{matrix}{t_{3\max} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}\tau_{{He}\; 0.m}}{\tau_{{He}\mspace{14mu} m\; i\; n} - \tau_{{He}\; 0.m}}{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}}{\tau_{{He}\; 0.m}} \right)}}} & {{formula}\mspace{14mu} 20}\end{matrix}$ for the fixed scheme, t_(3max) is obtained by formula 21,$\begin{matrix}\left. \begin{matrix}{t_{3\max} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}P_{{He}\; 0}}{{kP}_{0} - P_{{He}\; 0}}{\ln\left( \frac{{kP}_{0}}{P_{{He}\; 0}} \right)}}} \\{t_{3\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}}}\end{matrix} \right\} & {{formula}\mspace{14mu} 21}\end{matrix}$ for the helium-argon pressuring method after argonprefilling, when τ_(Hemin)>τ_(He0) and R_(1max)≥R_(0max), the maximumdetection-waiting time t_(2max) of fine-leak test is obtained by formula22, $\begin{matrix}{t_{2\max} = {{\frac{\tau_{{He}\mspace{14mu} m\; i\; n}\tau_{{He}\; 0}}{\tau_{{He}\mspace{14mu} m\; i\; n} - \tau_{{He}\; 0}}\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}}{\tau_{{He}\; 0}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\; 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} \right\rbrack}} \right\}} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}{VP}_{{He}\; 0}}{{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0\max}} - {VP}_{{He}\; 0}}\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0\max}}{{VP}_{{He}\; 0}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}R_{0\max}}{{VP}_{{He}\; 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} \right\rbrack}} \right\}}}} & {{formula}\mspace{14mu} 22}\end{matrix}$ for the fixed scheme, t_(2max) is obtained by formula 23,$\begin{matrix}\left. \begin{matrix}{t_{2\max} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}{VP}_{{He}\; 0}}{{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0\max}} - {VP}_{{He}\; 0}}\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}R_{0\max}}{{VP}_{{He}\; 0}} \right)} +} \right.}} \\{\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}R_{0\max}}{{VP}_{{He}\; 0}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} \right\rbrack} \\{t_{2\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}}}\end{matrix} \right\} & {{formula}\mspace{14mu} 23}\end{matrix}$ for the helium-argon pressuring method after argonprefilling, when τ_(Hemin)>τ_(He0), R_(1max)<R_(0max), t_(2max) isobtained by formula 24, $\begin{matrix}{t_{2\max} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}\tau_{{He}\;{0 \cdot m}}}{\tau_{{He}\mspace{14mu} m\; i\; n} - \tau_{{He}\;{0 \cdot m}}}\left\{ {{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}}{\tau_{{He}\; 0.m}} \right)} + {\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\; 0.m}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} \right\rbrack}} \right\}}} & {{formula}\mspace{14mu} 24}\end{matrix}$ for the fixed scheme, t_(2max) is obtained by formula 25,$\begin{matrix}\left. \begin{matrix}{t_{2\max} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}^{2}P_{{{He}\; 0}\;}}{{P_{E}t_{1}} - {P_{{He}\; 0}\tau_{{He}\mspace{14mu} m\; i\; n}}}\left\{ {{\ln\left( \frac{P_{E}t_{1}}{P_{{He}\; 0}\tau_{{He}\mspace{14mu} m\; i\; n}} \right)} +} \right.}} \\{\ln\left\lbrack \frac{1 - {\exp\left( {- \frac{P_{E}t_{1}^{2}}{P_{{He}\; 0}\tau_{{He}\mspace{14mu} m\; i\; n}^{2}}} \right)}}{1 - {\exp\left( {- \frac{t_{1}}{\tau_{{He}\mspace{14mu} m\; i\; n}}} \right)}} \right\rbrack} \\{t_{2\max} \leqslant {\frac{1}{10}\tau_{{He}\mspace{14mu} m\; i\; n}}}\end{matrix} \right\} & {{formula}\mspace{14mu} 25}\end{matrix}$ for the helium-argon pressuring method after argonprefilling, after the nth helium-argon pressuring, n is no less than 1,the maximum detection-waiting time is obtained by formula 26 whenτ_(Hemin)>τ_(He0) and R_(2n.max)≥R_(0max), $\begin{matrix}{t_{3{n.\max}} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}\tau_{{He}\; 0}}{\tau_{{He}\mspace{14mu} m\; i\; n} - \tau_{{He}\; 0}}{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}}{\tau_{{He}\; 0}} \right)}}} & {{formula}\mspace{14mu} 26}\end{matrix}$ in the condition of τ_(Hemin)>τ_(He0) andR_(2n.max)<R_(0max), t_(3n.max) is obtained by formula 27,$\begin{matrix}{t_{3{n.\max}} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}\tau_{{He}\; 0.m}}{\tau_{{He}\mspace{14mu} m\; i\; n} - \tau_{{He}\; 0.m}}{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}}{\tau_{{He}\; 0.m}} \right)}}} & {{formula}\mspace{14mu} 27}\end{matrix}$ for the helium-argon pressuring method after argonprefilling, after the nth helium-argon pressuring, where n is an integerno less than 2, maximum detection-waiting time t_(2n.max) of fine-leakis obtained by formula 28 when τ_(Hemin)>τ_(He0) andR_(1n.max)≥R_(0max), $\begin{matrix}{t_{2{n.\max}} = {\frac{\tau_{{He}\mspace{14mu} m\; i\; n}\tau_{{He}\; 0}}{\tau_{{He}\mspace{14mu} m\; i\; n} - \tau_{{He}\; 0}}{\ln\left( \frac{\tau_{{He}\mspace{14mu} m\; i\; n}}{\tau_{{He}\; 0}} \right)}}} & {{formula}\mspace{14mu} 28}\end{matrix}$ in the condition of τ_(Hemin)>τ_(He0) andR_(1n.max)<R_(0max), t_(2n.max) is obtained by formula 29,$\begin{matrix}{t_{2\;{n.\max}} = {\frac{\tau_{{He}\mspace{11mu}\min}\tau_{{He}\mspace{11mu} 0.m}}{\tau_{{He}\mspace{11mu}\min} - \tau_{{He}\mspace{11mu} 0.m}}{\ln\left( \frac{\tau_{{He}\mspace{11mu}\min}}{\tau_{{He}\mspace{11mu} 0.m}} \right)}}} & {{formula}\mspace{14mu} 29}\end{matrix}$ all the t_(max) are no less than 0.5 hour; t_(max)comprises t_(3max), t_(2max), t_(3n.max), and t_(2n.max), step S2.5, inorder to reduce or prevent detection missing in gross-leak test andfine-leak test, maximum gross-leak detection time t_(4max), fine-leakdetection time t_(5max) and minimum detection-waiting time ofhelium-argon prefilling method t_(3min) are designed as follows:t_(4max) is obtained by formula 30 when using one of the following fourtypical hermeticity test methods, which comprise helium-argon prefillingmethod, helium-argon pressuring method after argon prefilling,helium-argon pressuring method after helium-argon prefilling, andhelium-argon multi-pressuring method after argon prefilling,$\begin{matrix}\left. \begin{matrix}{t_{4\;\max} = {{\frac{1}{10}\tau_{{Ar}\; 0}} = {\frac{1}{10}\frac{V\; P_{{Ar}\; 0}}{R_{{Ar}\; 0\max}}}}} \\{{30\; s} \leqslant t_{4\;\max} \leqslant {900\mspace{14mu} s}}\end{matrix} \right\} & {{formula}\mspace{14mu} 30}\end{matrix}$ for the four typical hermeticity test methods, when themeasured leak rate criterion R_(max) of the fine-leak test is no lessthan 0.905R_(0max), R_(max) is obtained by formula 31, R_(max) comprisesR_(2max), R_(1max), R_(2n.max) and R_(1n.max), $\begin{matrix}\left. \begin{matrix}{t_{5\;\max} = {{\frac{1}{10}\tau_{{He}\; 0}} = {\frac{1}{10}\frac{V\; P_{0}}{L_{\; 0}}\sqrt{\frac{M_{He}}{M_{A}}}}}} \\{{60\; s} \leqslant t_{5\;\max} \leqslant {1200\mspace{14mu} s}}\end{matrix} \right\} & {{formula}\mspace{14mu} 31}\end{matrix}$ and for helium-argon prefilling method, t_(3min) isobtained by formula 32, $\begin{matrix}\left. \begin{matrix}\begin{matrix}\begin{matrix}{t_{3\;\min} = {\tau_{{He}\; 0}\frac{1}{1 + {10\; l_{{He}.n}}}}} \\{t_{3\;\min} \leqslant {\frac{1}{3}t_{3\;\max}}}\end{matrix} \\{or}\end{matrix} \\{t_{3\;\min} \leqslant {t_{3\;\max} - {24\; h}}}\end{matrix} \right\} & {{formula}\mspace{14mu} 32}\end{matrix}$ wherein, l_(He.n) is the viscous conductance constantcorresponding to L₀ when the pressures of both leak hole endsrespectively are P₀ and 0, and is obtained by formula 33,l _(He.n)=0.5L ₀ ^(0.314)  formula 33 for the four typical hermeticitytest methods, when R_(max) is less than 0.905R_(0max), t_(5max) isobtained by formula 34; $\begin{matrix}\left. \begin{matrix}{t_{5\;\max} = {\frac{{VP}_{{Ar}\; 0}}{R_{{Ar}\; 0\;\max}}\sqrt{\frac{M_{He}}{M_{Ar}}}{\ln\left( \frac{R_{0\;\max}}{R_{\max}} \right)}}} \\{{60\; s} \leqslant t_{5\;\max} \leqslant {1200\mspace{20mu} s}}\end{matrix} \right\} & {{formula}\mspace{14mu} 34}\end{matrix}$ step S2.6, the fixed scheme or flexible scheme is designedas follows: according to a certain cavity volume V, the selectedτ_(Hemin) and R_(Ar0max), the flexible scheme is designed for thecombination test with argon as gross-leak tracer gas and helium asfine-leak tracer gas; for the component under detection with acceptablehermeticity rigor grade τ_(Hemin), maximum equivalent standard leak rateL_(max) is obtained by formula 35, $\begin{matrix}{L_{\max} = {\frac{V\; P_{0}}{\tau_{{He}\mspace{11mu}\min}}\sqrt{\frac{M_{He}}{M_{A}}}}} & {{formula}\mspace{14mu} 35}\end{matrix}$ the range of cavity volume V for 0.0006 cm³˜200 cm³ isdivided into different segments, and then the fixed scheme of thehelium-argon prefilling method and helium-argon pressuring method afterargon prefilling is designed, R_(2max) is obtained by formula 3 andR_(1max) by formula 5; the lower limit of a cavity volume segment willbe used when designing R_(2max), R_(1max), t_(3max), t_(2max), t_(4max),t_(5max) and L_(max); similarly, the upper limit of V will be used whendesigning t_(3min); a step S3 of helium-argon prefilling or argonprefilling during sealing of the component under detection andhelium-argon pressuring, wherein for the helium-argon prefilling methodand helium-argon pressuring method after argon prefilling, the totalpressure of prefilling gas P is (1+10%)P₀ with the argon partialpressure of (1+10%)946 Pa and the helium partial pressure as follows:for helium-argon prefilling method, the helium pressure ratio k will be21% in fixed scheme, or designed by step S2 in flexible scheme, whereinthere is no helium in the prefilling gas for helium-argon pressuringmethod after argon prefilling; and for the fixed scheme and flexiblescheme of helium-argon pressuring method after helium-argon prefilling,the flexible scheme of helium-argon pressuring method after argonprefilling and helium-argon multi-pressuring method after argonprefilling, the argon pressure in helium-argon pressuring gas is(1+10%)946 Pa, and P_(E), and P_(En) are no less than 2P₀; a step S4 ofremoving the absorbed helium-argon and keeping the argon partialpressure P_(Ar0) and the helium partial pressure P_(He0) in normalatmosphere of the internal of the component under detection, wherein thecomponent under detection after sealing or helium-argon pressuring iskept in normal dry air environment with normal argon and helium partialpressure; and the component under detection is stayed in normal air for3.23 Δt at least to make the argon partial pressure of the componentunder detection get back to no less than 0.9 P_(Ar0) and the heliumpartial pressure get back to no less than 0.9P_(He0) if they experiencedvacuum baking or testing in the environment without normal helium andargon for Δt, Δt is no longer than ⅙t_(max); the argon leak ratecriterion change into 0.9R_(Ar0max) for gross-leak test and the heliumleak rate criterion is still R_(max) for fine-leak test; a step S6 ofcomparing the maximum detection-waiting time of the fine-leak test andminimum detection-waiting time of the fine-leak test, wherein forhelium-argon prefilling method, fine-leak test detection-waiting timet₃, which is from the ending of the sealing of the component underdetection and to the beginning of fine-leak test, is no longer thant_(3max) designed in step S2.4; when the fine-leak measured leak rateR_(2max)≥0.905R_(0max), t₃ is no less than t_(3min) designed in stepS2.5; and for the helium-argon pressuring method after argon prefilling,the helium pressuring method after helium-argon prefilling andhelium-argon multi-pressuring method after argon prefilling, the maximumdetection-waiting time t₂, t_(3n) and t_(2n) from the ending of the lasthelium-argon pressuring to the beginning of the combination test arerespectively no more than t_(2max), t_(3n.max), t_(2n.max) designed instep S2.4; if t₃>t_(3max), t₂>t_(2max), t_(3n)>t_(3n.max) ort_(2n)>t_(2n.max), the component under detection is pressuredhelium-argon and experienced removing absorbed helium-argon again beforetest; a step S7 of performing the gross-leak test, wherein gross-leakdetection time t₄, which is a time period from putting the componentunder detection in a detecting chamber, flushing and vacuuming thedetecting chamber to the beginning of reading the argon measured leakrate R_(Ar) of the gross-leak test, is no less than minimum gross-leakdetection time t_(4min) and no longer than t_(4max) designed in stepS2.5; t_(4min) is the longest time of background argon leak ratereducing to ⅓R_(Ar0max) in the condition of stable test system and emptychamber; and if the argon measured leak rate R_(Ar) is no less thanR_(Ar0max), the component is refused; if the argon measured leak rateR_(Ar) is less than R_(Ar0max), the component is accepted and thefine-leak test of the component under detection is proceeded; a step S8of performing the fine-leak test, wherein fine-leak detection time t₅,which is a time period from putting the component under detection in thedetecting chamber to the beginning of reading the argon measured leakrate R of the fine-leak test, is no less than the minimum fine-leakdetection time t_(5min) and no longer than t_(5max) designed in stepS2.5; t_(5min) is the longest time of background helium leak rate R_(b)reducing to ⅓R_(max) in the condition of stable test system and emptychamber; R_(max) comprises R_(2max), R_(1max), R_(2n.max) or R_(1n.max),and if the measured helium leak rate R is higher than R_(max), R is R₂,R₁, R_(2n), or R_(1n), the component under detection is refused, elsethe component under detection is accepted.
 2. The combination testmethod according to claim 1, further comprising a step S10 of thequantitative detection, wherein if quantitative detection τ_(He) or L ofis required, the method, flexible scheme, higher τ_(Hemin) and availablelower R_(Ar0max) are selected in step S1; helium-argon prefilling methodor helium-argon pressuring method after argon prefilling is selected forthe first hermeticity test, then helium-argon pressuring method afterhelium-argon prefilling or helium-argon multi-pressuring method afterargon prefilling is selected for the repetitive hermeticity test;according to a certain cavity volume V, the flexible scheme is designedin step S2.6; wherein, for helium-argon prefilling method, k=0.21, everytime the helium-argon pressuring time t_(1i) and the maximumdetection-waiting time t_(max), is shorter than 0.1τ_(Hemin), t_(max)comprises t_(3max), t_(2max), t_(3n.max), or t_(2n.max), the heliummeasured leak rate criterion R_(max) is given, R_(max) comprisesR_(2max), R_(1max), R_(2n.max), or R_(1n.max), so as to the relativetest condition of P_(E) or P_(En), t_(4max), t_(5max), t_(3min); in stepS8 of fine-leak test, some sample with same shape, which has beendetected and accepted, is used to prove absorbed helium leak rateR_(a)<0.1R_(max), the background helium measured leak rate R_(b) is readwhen the detecting chamber is empty, and the helium measured leak rate Rof the component under detection is read, which R comprises R₂, R₁,R_(2n), or R_(1n); for the accepted component in the condition ofτ_(He)≥τ_(Hemin), the real helium measured leak rate R′ is obtained byformula 36, R′ comprises R₂′, R₁′, R_(2n)′, or R_(1n)′,R′=R−R _(b)  formula 36 wherein, R′ contains absorbed helium leak rateand other system deviation, for the accepted component in hermeticitytest by using helium-argon prefilling method, the helium gas exchangeconstant τ_(He) is approximately obtained by formula 37 throughasymptotic fitting method, $\begin{matrix}{R_{2}^{\prime} = {\frac{V}{\tau_{He}}\left\lbrack {{k\; P_{0}\mspace{14mu}{\exp\left( {- \frac{t_{3}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\rbrack}} & {{formula}\mspace{14mu} 37}\end{matrix}$ in the condition of$t_{3} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}$ andkP₀≥10P_(He0), the gas exchange constant τ_(He) is approximatelyobtained by formula 38, $\begin{matrix}{\tau_{He} = {\tau_{{He}\mspace{11mu}\min}\frac{R_{2\;\max}}{R_{2}^{\prime}}}} & {{formula}\mspace{14mu} 38}\end{matrix}$ for the accepted component in hermeticity test by usinghelium-argon pressuring method after argon prefilling, the gas exchangeconstant τ_(He) is approximately obtained by formula 39 throughasymptotic fitting method, $\begin{matrix}{R_{1}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{{P_{E}\left\lbrack {1 - {\exp\left( {- \frac{t_{1}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\}}} & {{formula}\mspace{14mu} 39}\end{matrix}$ or it is obtained by formula 40 in the condition of${t_{1} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}},{t_{2} \leqslant {\frac{1}{10}\tau_{{He}\mspace{11mu}\min}}},{{P_{E}t_{1}\text{/}T_{He}} \geqslant {10\; P_{{He}\; 0}}},$$\begin{matrix}{\tau_{He} = {\tau_{{He}\mspace{11mu}\min}\sqrt{\frac{R_{1\;\max}}{R_{1}^{\prime}}}}} & {{formula}\mspace{14mu} 40}\end{matrix}$ for the accepted component in hermeticity test by usinghelium-argon pressuring method after helium-argon prefilling, τ_(He) isapproximately obtained by formula 41 through asymptotic fitting method,$\begin{matrix}{R_{2\; n}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{\left\{ {{k\; P_{0}\mspace{14mu}{\exp\left( {- \frac{t_{3.0\; n}}{\tau_{He}}} \right)}} + {\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1\; i}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{He}}} \right)}}}} \right\}{\exp\left( {- \frac{t_{2\; n}}{\tau_{He}}} \right)}} + P_{{He}\; 0}} \right\}}} & {{formula}\mspace{14mu} 41}\end{matrix}$ for the accepted component in hermeticity test by usinghelium-argon multi-pressuring method after argon prefilling, τ_(He) isapproximately obtained by formula 42 through asymptotic fitting method,$\begin{matrix}{R_{1\; n}^{\prime} = {\frac{V}{\tau_{He}}\left\{ {{\sum\limits_{i = 1}^{n}\;{{P_{Ei}\left\lbrack {1 - {\exp\left( {- \frac{t_{1\; i}}{\tau_{He}}} \right)}} \right\rbrack}{\exp\left( {- \frac{t_{2.{in}}}{\tau_{He}}} \right)}{\exp\left( {- \frac{t_{2\; n}}{\tau_{He}}} \right)}}} + P_{{He}\; 0}} \right\}}} & {{formula}\mspace{14mu} 42}\end{matrix}$ then the equivalent standard leak rate L is obtained byformula 43 when τ_(He) has been gotten, $\begin{matrix}{L = {\frac{{VP}_{0}}{\tau_{He}}\sqrt{\frac{M_{He}}{M_{A}}}}} & {{formula}\mspace{14mu} 43}\end{matrix}$ both of τ_(He) and L are the quantitative detectionresults with detection deviation.